HE  NEW  ART 
DF  FLYING 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


WALDEMAR  KAEMPFFERT 


LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 


Class 


THE  NEW  ART  OF  FLYING 


Photograph  by  Edwin  Levick 

Fig.   36. — The   Hanriot  monoplane  in   flight.     The 

entire  framework  is  covered  with  canvas 

to  reduce  resistance 


The 
New  Art  of  Flying 

BY 

WALDEMAR  KAEMPFFERT 

With  Numerous  Illustrations 

vi  , 

>-,  >'  T*  ;\  }  ,  -,  }  i     sTV%?  HI  £*;i 

NEW   YORK 
DODD,  MEAD  AND  COMPANY 
1911 

Copyright  iplO, 
BY  WALDEMAR  KAEMPFFERT 

Copyright  1911 
BY  HARPER  &  BROS. 

Published,  April,  1911 

LIBRARIAN'S  FIK3 


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PREFACE 

WHEN  the  time  comes  for  some  historian  of 
the  far-distant  future  to  survey  critically  the 
technical  achievements  of  the  nineteenth  and 
twentieth  centuries  and  to  weigh  the  compara- 
tive economic  importance  of  those  achievements, 
it  may  be  that  the  invention  of  the  aeroplane 
flying-machine  will  be  deemed  to  have  been  of 
less  material  value  to  the  world  than  the  dis- 
covery of  Bessemer  and  open-hearth  steel,  or 
the  perfection  of  the  telegraph,  or  the  intro- 
duction of  new  and  more  scientific  methods  in 
the  management  of  our  great  industrial  works. 
To  us,  however,  the  conquest  of  the  air,  to  use 
a  hackneyed  phrase,  is  a  technical  triumph  so 
dramatic  and  so  amazing  that  it  overshadows 
in  importance  every  feat  that  the  inventor  has 
accomplished.  If  we  are  apt  to  lose  our  sense 
of  proportion,  it  is  not  only  because  it  was  but 
yesterday  that  we  learned  the  secret  of  the  bird, 
but  also  because  we  have  dreamed  of  flying 
long  before  we  succeeded  in  ploughing  the  water 
in  a  dug-out  canoe. 

From  Icarus  to  the  Wright  Brothers  is  a  far 
cry.     In  the  centuries  that  have  elapsed  more 


218707 


vi  PREFACE 

lives  have  been  lost  in  aeronautic  experimenta- 
tion than  in  devising  telephones  and  telegraphs. 
These  tragedies  of  science  have  lent  a  glamour 
to  the  flying-machine;  so  much  so,  indeed,  that 
the  romance  rather  than  the  technique  of  flying 
interests  the  reading  public.  Yet  this  attitude 
of  wonder  is  pardonable.  Only  a  few  years  ago 
the  inventor  of  a  flying-machine  was  classed, 
even  by  scientists,  with  the  misguided  enthusi- 
ast who  spends  his  life  in  devising  perpetual 
motion  machines  or  in  fruitless  attempts  at 
squaring  the  circle.  It  is  hard  to  realise  that 
the  building  of  aeroplanes  is  now  elevated  to 
the  dignity  of  a  legitimate  engineering  pursuit. 

Although  the  romantic  aspects  of  aviation 
have  not  been  ignored  in  the  following  pages, 
it  is  the  chief  purpose  of  this  book  to  explain  as 
simply  and  accurately  as  possible  the  principles 
of  dynamic  flight  and  aeroplane  construction, 
so  that  an  intelligent  reader  will  learn  why  a 
machine  many  times  heavier  than  the  air  stays 
aloft  for  hours  at  a  time  and  why  it  is  con- 
structed as  it  is.  The  limitations  imposed  by 
a  popular  book  are  such  that  it  is  impossible  to 
discuss  with  anything  like  thoroughness  such 
difficult  matters  as  equilibrium  and  stability,  the 
correct  proportioning  of  supporting  surfaces  to 
weight  and  speed,  and  the  resistance  encoun- 


PREFACE  vii 

tered  in  the  air  by  planes  in  motion.  Indeed, 
these  questions  are  not  definitely  settled  in  the 
minds  of  technical  men.  Besides  presenting  an 
elementary  account  of  a  flying-machine's  way 
in  the  air,  it  has  been  deemed  advisable  to  dis- 
cuss the  screw  and  the  internal-combustion 
motor  as  applied  to  the  flying-machine.  There 
can  be  little  doubt  that  the  propeller  and  the 
engine  offer  many  a  problem  for  solution  be- 
fore the  aeroplane  can  compete  successfully  with 
other  forms  of  locomotion,  and  a  discussion  of 
the  driving  mechanism  of  an  aeroplane  should, 
therefore,  constitute  an  essential  part  of  even 
a  popular  book  on  flying. 

So  marked  have  been  the  changes  that  have 
been  made  in  the  construction  of  well-known 
biplanes  and  monoplanes  and  so  many  are  the 
new  machines  that  appear  almost  from  week 
to  week  that  it  is  almost  a  hopeless  task  to 
present  anything  like  a  complete  account  of 
existing  aeroplanes.  Hence  it  has  been  deemed 
advisable  to  limit  the  descriptions  of  types  to 
those  machines  which  have  been  in  a  measure 
standardized. 

In  the  preparation  of  this  volume  the  author 
has  been  ably  assisted  by  several  friends  to 
whom  he  wishes  to  make  due  acknowledgment. 
He  is  indebted  to  Mr.  Carl  Dienstbach  for  a 


viii  PREFACE 

critical  reading  of  the  entire  manuscript  before 
it  passed  to  the  press,  and  for  many  valuable 
suggestions;  to  Mr.  C.  Fitzhugh  Talman,  li- 
brarian of  the  United  States  Weather  Bureau, 
for  a  painstaking  revision  of  the  chapter  en- 
titled "  The  New  Science  of  the  Air  ";  to  Mr. 
H.  A.  Toulmin  for  information  on  the  points 
at  issue  in  the  various  suits  brought  by  the 
Wright  Brothers  for  the  alleged  infringement 
of  their  patents;  to  Francis  W.  Aymar,  Pro- 
fessor of  Law  in  the  New  York  University 
Law  School,  for  valuable  aid  in  the  prepara- 
tion of  the  chapter  on  "  The  Law  of  the 
Air  " ;  and  to  the  Smithsonian  Institution  and 
the  Wright  Brothers  for  various  photographs. 

Acknowledgment  is  also  made  to  Messrs. 
Harper  &  Brothers  for  permission  to  use  ma- 
terial which  appeared  in  an  article  written  by 
the  author  and  published  in  "  Harper's  Monthly 
Magazine." 

NEW  YORK,  N.  Y.,  January,  1911. 


CONTENTS 

CHAPTER  PAGI 

I     WHY  FLYING-MACHINES  FLY  ....  i 

II     FLYING-MACHINE  TYPES 15 

III  THE  PLANE  IN  THE  AIR 26 

IV  STARTING  AND  ALIGHTING 42 

V    How  AN  AEROPLANE  is  BALANCED      .  58 

VI     MAKING  A  TURN 85 

VII  THE  PROPELLER 94 

VIII  AEROPLANE  MOTORS in 

IX  THE  NEW  SCIENCE  OF  THE  AIR  .  .  133 

X  THE  PERILS  OF  FLYING 163 

XI  THE  FLYING-MACHINE  IN  WAR  .  .  .  185 

XII  SOME  TYPICAL  BIPLANES 208 

XIII  SOME  TYPICAL  MONOPLANES  ....  222 

XIV  THE  FLYING-MACHINE  OF  THE  FUTURE  23 1 
XV    THE  LAW  OF  THE  AIR        246 

GLOSSARY 269 

INDEX fc     .     .  281 


ILLUSTRATIONS 

Fig.  36. — The  Hanriot  monoplane  in  flight.  The  entire  frame- 
work is  covered  with  canvas  to  reduce  resistance  frontispiece 

FACING  PAGE 

Fig.     i .  —  Lilienthal  gliding  in  the  machine  in  which  he  was  killed         4 
Fig.     a.  —  Chanute  trussed  biplane  glider  in  flight 8 

fig.  3. —  Langley's  steam-driven  model,  the  first  motor  flying- 
machine  that  ever  flew ia 

Fig.  4.  —  Langley's  aerodrome  in  flight  on  May  6,  1X96,  on  the 
Potomac  River  at  Quantico.  This  is  the  first  photo- 
graph ever  made  of  an  aeroplane  in  flight  ....  1 6 

Fig.  5.  —  Roe's  triplane  in  flight.  The  best  engineering  opinion 
is  against  the  triplane  because  of  its  large  head  resist- 
ance and  consequent  low  speed 20 

Fig.  6.  —  Cornu's  helicopter  or  screw-flyer.  In  this  machine  the 
lifting  and  propulsive  force  is  obtained  entirely  by 
screws »4 

Fig.  IO.  —  Langley's  device  for  launching  his  aerodromes.  The 
machine  was  mounted  on  a  houseboat,  which  could  be 
turned  in  any  direction  so  as  to  face  the  wind  ...  30 

Fig.  1 1 .  —  Langley's  model  aerodrome  photographed  immediately 

after  a  launch  .  .  % 34 

Fig.  13.  —  Starting  derrick  and  rail  of  the  Wright  Brothers.  The 

machine  is  about  to  be  hauled  up  on  the  rails  ...  38 

Fig.  14.  —  Combined  wheels  and  skids  employed  on  the  later  Wright 

machines 44 

Fig.  15.  —  Bleriot  starting  from  the  French  coast  on  his  historic 

flight  across  the  English  Channel 48 

Fig.  ao.  —  Mr.  Wilbur  Wright  in  the  old  type  Wright  biplane       .       54 

Fig.  ai.  — The  first  type  of  Wright  biplane,  showing  the  general  dis- 
position of  the  main  planes,  forward  horizontal  rudders 
and  rear  vertical  rudders 60 

Fig.  aa.  —  A  machine  devised  by  the  Wrights  for  the  instruction  of 

pupils 7* 

Fig.  24.  —  Glenn  H.  Curtiss  winning  the  Scientific  American  Trophy 

on  July  4,  1908 76 

Fig.  25.  — Glenn  H.  Curtiss  in  one  of  his  flying-machines,  equipped 

with  balancing-planes  between  the  main  planes  .  .  80 

Fig.  27.  — The  Farman  biplane.  The  ailerons  are  the  flaps  on  the 
planes,  which,  as  shown  in  this  picture,  hang  down 
almost  vertically  when  the  machine  is  at  rest  ...  8z 

xi 


ILLUSTRATIONS 

FACING   PAGE 

Fig.  28.  —  Henry  Farman  seated  in  his  biplane.  His  hand  grasps 

the  lever  by  which  the  ailerons  are  operated  ...  88 

Fig.  29.  —  One  of  the  new  Curtiss  biplanes  in  flight.  The  ma- 
chine is  fitted  with  ailerons  similar  to  those  of  the 
Farman  machine  pictured  in  Fig.  27 92 

Fig.  32.  —  In  the  Antoinette  monoplane  the  horizontal  or  elevating 
rudder  is  operated  by  means  of  a  vertical  hand-wheel 
by  the  pilot's  right  hand.  The  aviator  here  pictured 
is  Hubert  Latham  .  o,g 

Fig-  33-  —  The  Antoinette  monoplane  of  1909  in  which  ailerons 

were  employed  to  control  the  machine  laterally  .  .  102 

Fig.  34.  —  Voisin  machine  of  1909.  Machines  such  as  this  are 

no  longer  made 106 

Fig-  35- — The  Voisin  biplane  of  1910.  The  old  cellular  con- 
struction is  abandoned.  Instead  of  vertical  curtains 
between  the  main  planes  Farman  ailerons  are  adopted  112 

Fig.  37.  —  Gyrostat  mounted  in  an  aeroplane  according  to  the  system 
of  A.  J.  Roberts.  The  gyrostat  is  controlled  by  a 
pendulum  which  swings  to  the  right  or  to  the  left, 
according  to  the  tilt  of  the  aeroplane  .  .  .  .  1 1 6 

Fig.  38.  — The  new  Wright  biplane  in  which  horizontal  or  elevat- 
ing rudder  is  mounted  in  the  rear 128 

Fig.  40.  —  A  Farman  biplane  making  a  turn.  The  entire  machine 
is  canted  so  that  its  weight  is  opposed  to  the  centrif- 
ugal force  generated  by  rounding  an  arc  at  high  speed  130 

Fig.  43.  —  A  Wright  propeller.  Wright  propellers  turn  at  com- 
paratively low  speeds  (400  revolutions  a  minute). 
They  have  an  estimated  efficiency  of  76  per  cent  .  136 

Fig.  44.  —  The  Wright  machine  is  driven  by  two  propellers  driven 
in  opposite  directions  by  chains  connecting  the  pro- 
peller shafts  with  the  motor  shaft 140 

Fig.  45. — The  Santos-Dumont  "Demoiselle"  monoplane  is  the 
smallest  flying-machine  that  has  ever  flown  success- 
fully with  a  man.  In  the  later  "Demoiselles" 
fabric  propellers  are  supplanted  by  wooden  screws  of 
the  usual  type 144 

Fig.  46.  —  A  Bleriot  monoplane  showing  a  seven-cylinder,  fifty- 
horse  power  rotary  Gnome  motor.  The  motor  spins 
around  with  the  propeller  at  the  rate  of  about  1400 
revolutions  a  minute 148 

Fig.  47.  —  The  motor  and  the  propeller  of  a  R.  E.  P.  (Robert 
Esnault-Pelterie)  monoplane.  Robert  Esnault-Pel- 
terie  has  abandoned  this  four-bladed  metal  propeller 
for  the  more  efficient  two-bladed  wooden  propeller  .  152 

Fig.  48.  —  Henry  Farman  seated  in  his  biplane  with  three  passengers     156 

xii 


ILLUSTRATIONS 

FACING   PAGE 

Fig.  63. — Motor  of  the  Wright  biplane 1 60 

Fig.  64.  — Two-cylinder  Anzani  motor  on  a  Letourd-Niepce  mono- 
plane   1 66 

Fig.  65. — The  kite  and  the  balloon-house  of  the  Mt.  Weather 

Observatory 17° 

Fig.  66.  —  Sending  up  the  first  of  a  pair  of  tandem  kites  at  the  Blue 

Hill  Observatory 174 

Fig.  67.  —  Mechanism  of  a  meteorograph  which  records  the  velocity 
of  the  wind,  the  temperature,  the  humidity,  and  the 
barometric  pressure 178 

Fig.  69.  — A  glimpse  through  a  Wright  biplane.  The  two  planes 
are  trussed  together  like  the  corresponding  members 
of  a  bridge,  so  as  to  obtain  great  strength  .  .  .  .  182 

Fig.  70.  —  One  of  the  numerous  accidents  that  happened  to  Louis 

,  Bleriot  before  he  devised  his  present  monoplane  .  .  1 88 

Fig.  71.  — A  biplane  that  came  to  grief  because  of  defective  lateral 

control IQ2 

Fig.  72.  —  An  old  style  Voisin  biplane  of  cellular  construction 
wrecked  because  the  pilot  tried  to  make  too  short  a 
turn  near  the  ground 196 

Fig.  73-  —  A  Krupp  6.5  cm.  gun  for  airship  and  aeroplane  attack. 
The  gun  fires  a  projectile  weighing  about  8  Ibs.  1 3  oz. 
to  a  height  of  about  18,700  feet 200 

Fig.  74.  —  A  Krupp  7. 5  cm.  gun  mounted  on  an  automobile  truck. 
The  gun  fires  a  12  Ib.  2  oz.  projectile  to  a  height 
of  about  4  miles.  The  automobile  has  a  speed  of 
28^  miles  an  hour.  Under  its  seats  62  projectiles 
can  be  stored 104 

Fig.  75.  — A  Krupp  10.5  cm.  naval  gun  for  repelling  aircraft  .     .     210 

Fig.  76.  —  The  projectiles  employed  for  the  repulsion  of  airships 
and  aeroplanes  leave  a  trail  of  smoke  behind  them  so 
that  the  gun  crew  can  determine  the  amount  of  error 
in  sighting 214 

Fig.  77.  —  A  projectile  that  hit  its  mark 216 

Fig.  78. ' —  A  Voisin  biplane  equipped  with  a  Hotchkiss  machine 
gun,  exhibited  at  the  1910  Salon  de  1'Aeronautique, 
Paris.  This  is  probably  the  first  attempt  to  mount 
a  machine  gun  on  an  aeroplane,  and  was  a  rather 
poor  attempt 2*O 

Fig.  79.  —  The  Wright  biplane  that  Wilbur  Wright  flew  in  France 

in  1908 224 

Fig.  80. — The  Wright  biplane  of  1910.  The  elevating  rudder 
has  been  placed  in  the  rear  of  the  machine,  where  it 
also  serves  as  a  tail 228 

xiii 


ILLUSTRATIONS 

_.  FACING  PAGE 

rig.  si.  — The  machine  in  the  air  is  a  Farman  biplane  of  the  latest 
type.  The  machine  on  the  ground  is  a  Bleriot 
monoplane 232 

Fig.  82. — Sommer  biplane 236 

Fig.  83.  — The  100  horsepower  Antoinette  monoplane  that  Hubert 
Latham  flew  at  Belmont  Park  during  the  Interna- 
tional Aviation  Tournament  of  1910  240 

Fig.  84.  —  The  Santos-Dumont  "  Demoiselle  "  in  flight      .     .     .     150 

Fig.  85.  —  A  Bleriot  racing  monoplane.  Six  men  are  exerting 

every  muscle  to  hold  back  the  machine  .  .  .  .  256 

Fig.  86.  —  The  Bleriot  monoplane  XII.  This  is  a  passenger- 
carrying  type.  The  pilot  and  his  companion  sit  side 
by  side  below  the  wings „  262 


XIV 


DIAGRAMS 

PAGE 

Fig.  7.  —  CD  is  the  "  entering  edge."  The  lifting  power  of  the 
forward  half  A  of  the  curved  plane  is  greater  than  the 
lifting  power  of  the  rear  half  2?,  although  both  are 
of  equal  area 28 

Fig.  8.  — A  is  a  simple  inclined  plane  j  S,  a  curved  plane  at  the 
same  angle  of  incidence  or  inclination ;  C,  the  type 
of  curved  plane  which  has  thus  far  given  the  best 
results  in  the  air 29 

Fig-  9 .  —  The  plane  B  S  is  at  a  greater  angle  of  incidence  than 
the  plane  A  A.  If  its  speed  be  10  miles  an  hour,  it 
will,  while  travelling  horizontally  25  feet,  overcome 
its  tendency  to  fall  to  D.  If  its  speed  be  20  miles 
an  hour,  it  will  have  50  feet  to  travel  while  over- 
coming its  tendency  to  fall  to  E.  Unless  the  angle 
of  B  S,  therefore,  were  decreased  to  that  of  A  A  for 
the  greater  speed,  the  plane  would  not  move  hori- 
zontally but  would  ascend 32 

Fig.  12. — The  special  launching  device  invented  by  the  Wright 
Brothers.  The  device  consists  of  an  inclined  rail, 
about  seventy  feet  long  ;  a  pyramidal  derrick  j  a  heavy 
weight  arranged  to  drop  within  the  derrick ;  and  a 
rope,  which  is  fastened  to  the  weight,  passed  around 
a  pulley  at  the  top  of  the  derrick,  then  around  a  second 
pulley  at  the  bottom  of  the  derrick  over  a  third  pulley 
at  the  end  of  the  rail,  and  finally  fastened  to  a  car 
running  on  the  rail.  The  car  is  placed  on  the  rail, 
and  the  aeroplane  on  the  car.  When  a  trigger  is 
pulled,  the  weight  falls,  and  the  car  is  jerked  forward. 
So  great  is  the  preliminary  velocity  thus  imparted  that 
the  machine  is  able  to  rise  in  a  few  seconds  from  the 
car,  which  is  left  behind 52 

Fig.  1 6.  —  Path  of  an  aeroplane  driven  forward  but  with  a  speed  too 

low  for  horizontal  flight,  and  with  too  flat  an  angle  .  58 

Fig.  17 — Path  of  a  plane  inclined  at  the  angle  C  to  the  horizontal. 
The  arrow  A  indicates  the  direction  of  travel.  If  the 
speed  is  sufficient  the  plane  will  rise  because  of  the 
upward  inclination  of  the  plane 59 

Fig.  18. —  How  a  plane  is  laterally  balanced  by  means  of  ailerons 
and  a  vertical  rudder.  — The  plane  A  is  provided  with 
hinged  tips  C  and  D  and  with  a  vertical  rudder  E. 
The  tips  are  swung  in  opposite  directions  to  correct 
any  tipping  of  the  plane,  and  the  vertical  rudder  E  is 

XV 


DIAGRAMS 

PACK 

swung  over  to  the  side  of  least  resistance  (the  side  of  the 
tip  D  in  the  example  here  given)  in  order  to  prevent 
the  entire  machine  from  rotating  on  a  vertical  axis     .        62 
Fig.  19. —  The  system  of  control  on  an  old  Wright  model  ...       64 

Fig.  13.  —  The  Curtiss  system  of  control 66 

Fig.  26.  —  The  system  of  ailerons  and  rudders  devised  by  Henry 
Farman  for  maintaining  fore-and-aft  and  side-to-side 
balance 68 

Fig.  30.  —  The  Bleriot  system  of  control 70 

Fig.  31. — The  steering  and  control  column  of  the  Bleriot  mono- 
plane. The  wheel  Z,,  the  post  AT,  and  the  bell-shaped 
member  M  form  one  piece  and  move  together.  Wires 
0  connect  the  bell  with  the  yoke  G,  carrying  the 
pulley  F,  around  which  the  wires  H  running  to  the 
flexible  portions  of  the  supporting  planes  are  wrapped. 
By  rocking  the  post  and  bell  from  side  to  side  in  a 
vertical  plane  the  wires  H  are  respectively  pulled  and 
relaxed  to  warp  the  planes.  By  moving  the  post  K 
back  and  forth  the  horizontal  rudder  is  operated  through 
the  wires  P.  These  various  movements  of  the  post 
can  be  effected  by  means  of  the  wheel  L,  which  is 
clutched  by  the  aviator's  hands,  or  by  means  of  the 
bell  My  which  can  be  clutched  by  the  aviator's  feet 
if  necessary 71 

Fig.  39.  —  An  aeroplane  of  40  feet  spread  of  wing  rounding  an  arc 
of  60  feet  radius.  Since  the  outer  side  of  the  aeroplane 
must  travel  over  a  given  distance  in  the  same  time  that 
the  inner  side  must  travel  a  considerably  shorter  distance, 
gravitation  must  be  opposed  to  centrifugal  force  in 
order  that  the  turn  may  be  effected  with  safety  .  .  86 

Fig.  41.  —  A  single-threaded  and  a  double- threaded  screw.  A  two- 
bladed  aeroplane  propeller  may  be  conceived  to  have 
been  cut  from  a  double-threaded  screw,  /.  «.,  the  sec- 
tions AznA  A'  and  the  sections  B  and  B'  ...  97 

Fig.  42.  —  How  the  Wright  propeller  is  cut  from  three  planks  laid 

upon  one  another  fan-wise 109 

Figs.  49,  50,  51,  and  52. —  The  four  periods  of  a  four-cycle  engine. 
During  the  first  period  (Fig.  49)  the  explosive  mix- 
ture is  drawn  in ;  during  the  second  period  (Fig.  50) 
the  explosive  mixture  is  compressed  j  during  the  third 
period  (Fig.  51)  the  mixture  is  exploded  ;  and  during 
the  fourth  period  the  products  of  combustion  are 
discharged 114 

FiS*  53 • — The  U8ual  arrangement  of  the  four  cylinders  of  a  four- 
cylinder  engine  ..........  .118 

xvi 


DIAGRAMS 

PAGE 

Figs,  54  and  55.  —  Side  and  plan  views  of  a  four-cylinder  engine 

with  diagonally-placed  cylinders 120 

Figs.  56  and  57.  —  Engine  with  horizontally  opposed  cylinders  .     .      1 21 

Figs.  58  and  59.  — Engine  with  four  cylinders  radially  arranged       .     123 

Fig.  60.  —  Arrangement  of  connecting-rods  of  an  engine  with  four 

radial  cylinders ..124 

Fig.  6 1  —  Arrangement  of  cylinders  and  crank  case  of  one  type  of 

three-cylinder  engine ....125 

Fig.  62.  —  Disposition  of  cylinders,  crank  case  and  connecting-rods 

in  one  type  of  engine 126 

Fig.  68.  —  The  extent  of  the  atmosphere  in  a  vertical  direction. 

Heights  in  kilometres     ..••••••.147 


XV11 


THE 

NEW    ART    OF    FLYING 
CHAPTER    I 

WHY   FLYING-MACHINES   FLY 

AN  aeroplane  is  any  flat  or  slightly  curved  sur- 
face propelled  through  the  air.  Since  it  is  con- 
siderably heavier  than  air,  an  inquiring  mind 
may  well  ask:  Why  does  it  stay  aloft?  Why 
does  it  not  fall? 

It  is  the  air  pressure  beneath  the  plane  and 
the  motion  of  the  plane  that  keep  it  up.  A 
balloon  can  remain  stationary  over  a  given  spot 
in  a  calm,  but  an  aeroplane  must  constantly 
move  if  it  is  to  remain  in  the  air.  The  mono- 
planes and  biplanes  of  Bleriot,  Curtiss,  and  the 
Wrights  are  somewhat  in  the  position  of  a 
skater  on  thin  ice.  The  skater  must  move  fast 
enough  to  reach  a  new  section  of  ice  before  he 
falls;  the  aeroplane  must  move  fast  enough 
to  reach  a  new  section  of  air  before  it  falls. 
Hence,  the  aeroplane  is  constantly  struggling 
with  gravitation. 


2       THE    NEW    ART    OF    FLYING 

The  simplest  and  most  familiar  example  of 
an  aeroplane  is  the  kite  of  our  boyhood  days. 
We  all  remember  how  we  kept  it  aloft  by  hold- 
ing it  against  the  wind  or  by  running  with  it  if 
there  happened  to  be  only  a  gentle  breeze. 
When  the  wind  stopped  altogether  or  the  string 
broke,  the  kite  fell.  Above  all  things  it  was 
necessary  to  hold  the  kite's  surface  toward  the 
wind,  —  an  end  which  we  accomplished  with  a 
string. 

The  eagle  is  an  animated  kite  without  a  string ; 
it  keeps  its  outspread  wings  to  the  wind  by 
muscular  power.  If  we  can  find  a  substitute  for 
the  string,  some  device  in  other  words  which 
will  enable  us  to  hold  the  kite  in  the  proper 
direction,  we  have  invented  a  flying-machine. 
The  pull  or  the  thrust  of  an  engine-driven  pro- 
peller is  the  accepted  substitute  for  the  string  of 
a  kite  and  the  muscles  of  an  eagle. 

If  only  these  simple  principles  were  involved 
in  a  solution  of  the  age-old  problem  of  artificial 
flight,  aeroplanes  would  have  skimmed  the  air 
decades  ago.  Many  other  things  must  be 
considered  besides  mere  propelling  machinery. 
Chief  among  these  is  the  very  difficult  art  of 


WHY    FLYING-MACHINES    FLY     3 

balancing  the  plane  so  that  it  will  glide  on  an 
even  keel.  Even  birds  find  it  hard  to  maintain 
their  balance.  In  the  constant  effort  to  steady 
himself  a  hawk  sways  from  side  to  side  as  he 
soars,  like  an  acrobat  on  a  tight  rope.  Occa- 
sionally a  bird  will  catch  the  wind  on  the  top  of 
his  wing,  with  the  result  that  he  will  capsize  and 
fall  some  distance  before  he  can  recover  himself. 
If  the  living  aeroplanes  of  nature  find  the  feat 
of  balancing  so  difficult,  is  it  any  wonder  that 
men  have  been  killed  in  endeavouring  to  dis- 
cover their  secret? 

If  you  have  ever  watched  a  sailing  yacht  in 
a  stiff  breeze  you  will  readily  understand  what 
this  task  of  balancing  an  aeroplane  really 
means,  although  the  two  cases  are  mechani- 
cally not  quite  parallel.  As  the  pressure  of  the 
wind  on  the  sail  heels  the  boat  over,  the  ballast 
and  the  crew  must  be  shifted  so  that  their 
weight  will  counterbalance  the  wind  pressure. 
Otherwise  the  yacht  will  capsize.  In  a  yacht 
maintenance  of  equilibrium  is  comparatively 
easy;  in  an  aeroplane  it  demands  incessant 
vigilance,  because  the  sudden  slight  variations 
of  the  wind  must  be  immediately  met.  The 


4      THE    NEW   ART    OF    FLYING 

aeroplane  has  weight;  that  is,  it  is  always  fall- 
ing. It  is  kept  aloft  because  the  upward  air 
pressure  is  greater  than  the  falling  force.  The 
weight  or  falling  tendency  is  theoretically  con- 
centrated in  a  point  known  as  the  centre  of 
gravity.  Opposed  to  this  gravitative  tendency 
is  the  upward  pressure  of  the  air  against  the 
under  surface  of  the  plane,  which  effect  is 
theoretically  concentrated  in  a  point  known 
as  the  centre  of  air  pressure.  Gravitation 
(weight)  is  constant;  the  air  pressure,  because 
of  the  many  puffs  and  gusts  of  which  even  a 
zephyr  is  composed,  is  decidedly  inconstant. 
Hence,  while  the  centre  of  gravity  remains  in 
approximately  the  same  place,  the  centre  of 
air  pressure  is  as  restless  as  a  drop  of  quick- 
silver on  an  unsteady  glass  plate. 

The  whole  art  of  maintaining  the  side-to- 
side  balance  of  an  aeroplane  consists  in  keeping 
the  centre  of  gravity  and  the  centre  of  air 
pressure  on  the  same  vertical  line.  If  the 
centre  of  air  pressure  should  wander  too  far 
away  from  that  line  of  coincidence,  the  aero- 
plane is  capsized.  The  upward  air  pressure 
being  greater  than  the  falling  tendency  and 


WHY    FLYING-MACHINES    FLY     5 

having  been  all  thrown  to  one  side,  the  aero- 
plane is  naturally  upset. 

Obviously  there  are  two  ways  of  maintain- 
ing side-to-side  balance,  —  the  one  by  con- 
stantly shifting  the  centre  of  gravity  into  coin- 
cidence with  the  errant  centre  of  air  pressure; 
the  other  by  constantly  shifting  the  centre  of  air 
pressure  into  coincidence  with  the  centre  of 
gravity. 

The  first  method  (that  of  bringing  the  centre 
of  gravity  into  alignment  with  the  centre  of  air 
pressure)  involves  ceaseless,  flash-like  move- 
ments on  the  part  of  the  aviator;  for  by  shift- 
ing his  body  he  shifts  the  centre  of  gravity.  It 
happened  that  one  of  the  first  modern  experi- 
menters with  the  aeroplane  met  a  tragic  death 
after  he  had  succeeded  in  making  over  two 
thousand  short  flights  in  a  gliding-machine  of 
his  own  invention,  simply  because  he  was  not 
quick  enough  in  so  throwing  his  weight  that 
the  centres  of  air  pressure  and  gravity  coin- 
cided. He  was  an  engineer  named  Otto  Lilien- 
thal,  and  he  was  killed  in  1896.  Birds  were 
to  him  the  possessors  of  a  secret  which  he  felt 
that  scientific  study  could  reveal.  Accordingly, 


6      THE    NEW   ART   OF    FLYING 

he  spent  many  of  his  days  in  the  obscure 
little  hamlet  of  Rhinow,  Prussia.  The  cottage 
roofs  of  that  hamlet  were  the  nesting  places  of 
a  colony  of  storks.  He  studied  the  birds  as 
if  they  were  living  machines.  After  some 
practical  tests,  he  invented  a  bat-like  appa- 
ratus composed  of  a  pair  of  fixed,  arched 
wings  and  a  tail-like  rudder.  Clutching  the 
horizontal  bar  to  which  the  wings  were  fast- 
ened, he  would  run  down  a  hill  against  the  wind 
and  launch  himself  by  leaping  a  few  feet  into 
the  air.  In  this  manner  he  could  finally  soar 
for  about  six  hundred  feet,  upheld  merely  by 
the  pressure  of  the  air  beneath  the  outstretched 
wings.  In  order  to  balance  himself  he  was  com- 
pelled to  shift  his  weight  incessantly  so  that  the 
centre  of  gravity  coincided  with  the  centre  of 
air  pressure.  Since  they  rarely  remain  coin- 
cident for  more  than  a  second,  Lilienthal  had 
to  exercise  considerable  agility  to  keep  his 
centre  of  gravity  pursuing  the  centre  of  air 
pressure,  which  accounts  for  the  apparently 
crazy  antics  he  used  to  perform  in  flights.  One 
day  he  was  not  quick  enough.  His  machine 
was  capsized,  and  his  neck  was  broken.  Pil- 


WHY    FLYING-MACHINES    FLY     7 

cher,  an  Englishman,  slightly  improved  on  Lili- 
enthal's  apparatus,  and  after  several  hundred 
flights  came  to  a  similar  violent  end.  Crude 
as  Lilienthal's  machine  undoubtedly  was,  it 
startled  the  world  when  its  first  flights  were 
made.  It  taught  the  scientific  investigator  of 
the  problem  much  that  he  had  never  even 
suspected,  and  laid  the  foundation  for  later 
researches. 

Octave  Chanute,  a  French  engineer  resident 
in  the  United  States,  continued  the  work  of  the 
ill-fated  Lilienthal.  Realising  the  inherent 
danger  of  a  glider  in  which  the  operator  must 
adapt  himself  to  the  changing  centre  of  air 
pressure  with  lightning-like  rapidity,  he  devised 
an  apparatus  in  which  the  centre  of  air  pressure 
was  made  to  return  into  coincidence  with  the 
centre  of  gravity,  —  the  second  of  the  two  ways 
of  maintaining  side-to-side  balance.  Thus 
Chanute  partly  removed  the  perilous  necessity 
of  indulging  in  aerial  gymnastics.  In  his  glid- 
ing-machines the  tips  of  the  planes,  when  struck 
by  a  gust  of  wind,  would  fold  slightly  backward, 
thereby  curtailing  the  tendency  of  the  centre 
of  air  pressure  to  shift. 


8      THE    NEW   ART   OF    FLYING 

Chanute  built  six  motorless,  man-carrying 
gliders,  with  three  of  which  several  thousand 
short  flights  were  successfully  undertaken.  The 
best  results  were  obtained  with  an  apparatus 
consisting  of  two  superposed  planes,  a  construc- 
tion which  had  been  previously  adopted  by 
Lilienthal.  It  remained  for  the  Wright 
Brothers  to  provide  a  more  perfect  mechanism 
for  controlling  the  movement  of  the  centre  of 
air  pressure. 

The  principle  of  sitting  or  lying  still  in  the 
aeroplane  and,  by  means  of  mechanical  devices, 
bringing  the  centre  of  air  pressure  back  into 
alignment  with  the  centre  of  gravity  is  now  fol- 
lowed by  every  designer  of  aeroplanes.  The 
old,  dangerous  method  of  shifting  weights  is 
quite  abandoned.  The  greatest  contribution 
made  by  the  Wright  Brothers  to  the  art  of  fly- 
ing was  that  of  providing  a  trustworthy  mech- 
anism for  causing  the  centre  of  air  pressure 
to  return  into  coincidence  with  the  centre  of 
gravity. 

The  aeroplane  must  be  balanced  not  only 
from  side-to-side  but  fore-and-aft  as  well.  The 
same  necessity  exists  in  the  eld-fashioned, 


WHY    FLYING-MACHINES    FLY     9 

single-surface  kite.  To  give  it  the  necessary 
fore-and-aft  stability,  we  used  to  adorn  it  with 
a  long  tail  of  knotted  strips  of  rags.  If  the  tail 
was  not  heavy/  or  long  enough,  the  kite  dived 
erratically  and  sometimes  met  its  destruction 
by  colliding  with  a  tree.  To  insure  longitud- 
inal stability,  many  aeroplane  flying-machines 
are  similarly  provided  with  a  tail,  which  con- 
sists generally  of  one  or  more  horizontal  plane 
surfaces.  Some  aeroplanes,  however,  are  tail- 
less, among  them  the  earlier  Wright  machines. 
Usually,  they  are  less  stable  than  the  tailed 
variety. 

In  order  to  relieve  the  .aviator  of  the  neces- 
sity of  more  or  less  incessantly  manipulating 
levers,  which  control  centres  of  air  pressure, 
many  inventors  have  tried  to  provide  aero- 
planes with  devices  which  will  perform  that 
task  automatically.  Some  of  them  are  ingen- 
ious; but  most  of  them  are  impracticable  be- 
cause they  are  too  heavy,  too  complicated,  or 
not  responsive  enough. 

In  order  to  fly,  an  aeroplane,  like  a  kite  or 
a  soaring  bird,  is  made  to  rise  preferably  in 
the  very  teeth  of  the  wind.  What  is  more,  it 


io    THE    NEW   ART   OF    FLYING 

must  be  in  motion  before  it  can  fly.  How  this 
preliminary  motion  was  to  be  obtained  long 
baffled  the  flying-machine  inventor.  Eagles, 
vultures,  and  other  soaring  birds  launch  them- 
selves either  by  leaping  from  the  limb  of  a 
tree  or  the  edge  of  a  cliff,  or  by  running  along 
the  ground  with  wings  outspread,  until  they 
have  acquired  sufficient  speed.  To  illustrate 
the  difficulty  that  even  practised  soaring  birds 
find  in  rising  from  the  ground,  the  late  Prof. 
Samuel  P.  Langley  used  to  quote  the  following 
graphic  description  of  the  commencement  of 
an  eagle's  flight  (the  writer,  one  of  the  founder 
members  of  the  old  aeronautical  society  of 
Great  Britain,  was  in  Egypt,  and  the  "  sandy 
soil  "  was  that  of  the  banks  of  the  Nile)  : 

"  An  approach  to  within  80  yards  arouses 
the  king  of  birds  from  his  apathy.  He  partly 
opens  his  enormous  wings,  but  stirs  not  yet 
from  his  station.  On  gaining  a  few  feet 
more  he  begins  to  walk  away  with  half- 
expanded,  but  motionless,  wings.  Now  for  the 
chance.  Fire !  A  charge  of  No.  3  from  eleven 
bore  rattles  audibly  but  ineffectively  upon  his 


WHY    FLYING-MACHINES    FLY  n 

densely  feathered  body;  his  walk  increases  to 
a  run,  he  gathers  speed  with  his  slowly  wav- 
ing wings,  and  eventually  leaves  the  ground. 
Rising  at  a  gradual  inclination,  he  mounts  aloft 
and  sails  majestically  away  to  his  place  of 
refuge  in  the  Libyan  range,  distant  at  least 
five  miles  from  where  he  rose.  Some  frag- 
ments of  feathers  denote  the  spot  where  the 
shot  has  struck  him.  The  marks  of  his  claws 
were  traceable  in  the  sandy  soil,  as,  at  first 
with  firm  and  decided  digs,  he  forced  his  way; 
but  as  he  lightened  his  body  and  increased  his 
speed  with  the  aid  of  his  wings,  the  imprints 
of  his  talons  gradually  merged  into  long 
scratches.  The  measured  distance  from  the 
point  where  these  vanished  to  the  place  where 
he  had  stood  proved  that  with  all  the  stimulus 
that  the  shot  must  have  given  to  his  exertions 
he  had  been  compelled  to  run  full  20  yards 
before  he  could  raise  himself  from  the  earth." 

We  have  not  all  had  a  chance  of  seeing  this 
striking  illustration  of  the  necessity  of  get- 
ting up  speed  before  soaring,  but  many  of 
us  have  disturbed  wild  ducks  on  the  water 


12    THE    NEW   ART    OF    FLYING 

and  noticed  them  run  along  it,  flapping  their 
wings  for  some  distance  to  get  velocity  before 
they  could  fly,  and  the  necessity  of  initial 
velocity  is  at  least  as  great  with  an  artificial 
flying-machine  as  it  is  with  a  bird.  From  this, 
we  can  readily  understand  why  a  vulture  can 
be  confined  in  a  small  cage,  which  is  entirely 
open  at  the  top. 

To  get  up  preliminary  speed  many  methods 
have  been  adopted.  Langley  tried  every  con- 
ceivable way  of  starting  his  small  model,  and 
at  last  hit  on  the  idea  of  launching  it  from 
ways,  somewhat  as  a  ship  is  launched  into  the 
water.  The  model  rested  on  a  car  which  fell 
down  at  the  extremity  of  its  motion  and  thus 
released  the  model  for  its  free  flight.  On 
May  6,  1896,  he  saw  his  creation  really  fly 
like  a  living  thing,  the  first  time  in  history  that 
a  motor-driven  aeroplane  ever  flew. 

The  Wright  Brothers  used  to  obtain  their 
preliminary  speed  by  having  their  machine 
carried  down  the  side  of  a  sandhill,  partly  sup- 
ported by  a  head-wind.  Their  first  perfected 
motor-driven,  man-carrying  biplane  was  started 
on  an  inclined  track.  Most  aviators  of  the 


O       (D 

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1  S 
1 


bfl 

j 


WHY    FLYING-MACHINES    FLY   13 

present  time,  however,  mount  their  aeroplanes 
on  pneumatic-tired  wheels,  and  like  the  eagle, 
in  the  foregoing  quotation,  run  along  the 
ground  for  a  short  distance.  Aeroplanes  have 
also  been  dropped  into  the  air  from  balloons. 

Just  as  a  soaring  bird  uses  his  legs  in  leap- 
ing into  the  air  or  running  on  the  ground  to 
start  his  flight  and  also  in  alighting,  so  many 
aeroplanes  alight  with  the  wheels  that  serve 
them  during  the  brief  moments  of  launching. 
Sometimes,  however,  special  alighting  devices 
are  provided,  a  conspicuous  example  of  which 
is  to  be  found  in  the  skids  or  runners  of  the 
Wright  machine. 

The  problem  of  steering  an  aeroplane,  when 
it  is  launched,  is  solved,  as  it  must  be,  by  two 
sets  of  rudders.  A  steamboat  is  a  vehicle  that 
travels  in  two  dimensions  only;  hence,  it  re- 
quires only  a  single,  vertical  rudder,  which 
serves  to  guide  it  from  side  to  side.  An  aero- 
plane moves  not  only  from  side  to  side,  but 
up  and  down  as  well.  Hence,  it  is  equipped 
with  a  vertical  rudder  similar  to  that  of  a 
steamboat's,  and  also  with  a  horizontal  rudder, 
which  serves  to  alter  its  course  up  or  down, 


14    THE    NEW   ART   OF    FLYING 

and  which  is  becoming  more  widely  known  as 
an  elevator.  Fore-and-aft  stability  is  attained 
in  tailless  machines  entirely  by  manipulation 
of  this  elevator.  Even  in  tailed  machines  its 
use  for  that  purpose  is  quite  imperative. 


CHAPTER   II 

FLYING-MACHINE  TYPES 

THE  flying  creatures  of  nature  —  insects, 
birds,  fishes,  and  bats  —  spread  wings  that  lie 
in  a  single  plane.  Because  their  wings  are  thus 
disposed  birds  may  be  properly  regarded  as 
single-decked  flying-machines  or  "  monoplanes," 
in  aviation  parlance,  and  because  the  earliest 
attempts  at  flying  were  more  or  less  slavish  imi- 
tations of  bird-flight,  it  was  but  natural  that 
the  monoplane  was  man's  first  conception  of  a 
flying-machine.  Since  birds  are  the  most  effi- 
cient flying-machines  known,  so  far  as  power 
consumption  for  distance  travelled  and  surface 
supported  are  concerned,  the  monoplane  will 
probably  always  be  regarded  as  the  ideal  type 
of  aeroplane  flying-machine. 

It  is  a  circumstance  of  considerable  scientific 
moment  that  the  wings  of  a  gliding  bird,  such 
as  an  eagle,  a  buzzard,  or  a  vulture,  are  wide 
in  spread  and  narrow  in  width.  Much  pains- 
taking experimentation  by  Langley  and  others 


1 6    THE    NEW   ART   OF    FLYING 

has  shown  that  the  best  shape  of  plane  is  that 
which  is  oblong;  the  span  must  be  considerably 
greater  than  the  width.  In  other  words,  science 
has  experimentally  approved  the  design  of  a 
bird's  wings.  In  nature  the  proportion  of  span 
to  width  varies  in  different  birds.  The  spread 
of  an  albatross'  wings  is  fourteen  times  the 
width;  the  spread  of  a  lark's  wings  is  four  times 
the  width,  which  is  the  smallest  ratio  to  be 
found  among  birds.  The  albatross  is  a  more 
efficient  flying-machine  than  the  lark.  Hence  the 
albatross  is  a  better  model  to  follow  and  four- 
teen to  one  a  better  ratio  than  four  to  one. 

Long  spans  are  unwieldy,  often  too  unwieldy 
for  practical,  artificial  flight.  Suppose  we  cut 
a  long  plane  in  half  and  mount  one  half  over 
the  other.  The  result  is  a  two-decked  machine, 
a  "  biplane."  Such  a  biplane  has  somewhat 
less  lifting  power  than  the  original  monoplane, 
and  yet  it  has  the  same  amount  of  entering 
edge.  Moreover,  the  biplane  is  a  little  steadier 
in  the  air  than  the  monoplane  and  therefore 
a  little  safer,  just  as  a  box-kite  is  steadier  than 
the  old-fashioned  single-surface  kite.  Still, 
the  difference  in  stability  between  biplane  and 


From  an  instantaneous  photograph  by  Dr.  Alexander  Graham  Bell 

Fig.   4. — Langley's  aerodrome   in   flight  on   May  6, 

1896,    on    the    Potomac    River    at    Quantico. 

This  is  the  first  photograph  ever  made 

of  an  aeroplane  in  flight 


FLYING-MACHINE   TYPES        17 

monoplane  is  so  slight  that  designers  base 
their  preferences  for  one  type  or  the  other  on 
other  considerations.  Both  types  are  inher- 
ently so  unstable  that  it  requires  a  skilled  hand 
to  correct  their  capsizing  tendencies. 

By  placing  one  plane  over  another  certain 
structural  advantages  are  obtained.  It  is  com- 
paratively easy  to  tie  two  superposed  planes 
together  and  to  form  a  strong,  bridge-like  truss, 
which  was  first  done  by  Chanute.  The  proper 
support  of  the  outstretched  surfaces  of  a  mono- 
plane, on  the  other  hand,  is  a  matter  of  some 
difficulty. 

To  correct  the  inherent  instability  of  both 
monoplanes  and  biplanes  and  to  make  them 
safer  machines,  tails  are  frequently  added. 
Stability  and  safety  are  thus  gained  at  the 
expense  of  driving  power;  for  the  increased 
surface  of  the  tail  means  more  resisting  sur- 
face and  therefore  less  speed.  An  engine  of 
twenty  horse-power  will  drive  a  tailless  Wright 
machine;  tailed  Voisin  machines  with  large, 
heavy  cellular  tails  have  refused  to  rise  at 
times  even  when  equipped  with  fifty  horse- 
power motors. 


1 8     THE    NEW   ART    OF    FLYING 

If  a  monoplane  were  to  fall  vertically  like 
a  parachute,  it  would  offer  the  resistance  of  its 
entire  surface  to  the  fall;  if  a  biplane  were  to 
fall,  it  would  offer  the  resistance  of  only  one 
of  its  planes  to  the  fall.  Hence  the  monoplane 
is  a  better  parachute  than  the  biplane.  The 
point  is  perhaps  of  slight  value,  because  if  a 
skilful  aviator  is  high  enough  when  his  motor 
fails  him,  he  can  always  glide  to  the  ground 
on  a  slant  which  may  be  miles  in  length.  Para- 
doxical as  it  may  seem,  the  greater  the  distance 
through  which  he  may  fall,  the  better  are  an 
aviator's  chances  of  reaching  the  ground  with 
an  unbroken  neck.  At  a  slight  elevation  from 
the  ground,  both  monoplanes  and  biplanes  are 
in  a  precarious  position  in  case  of  motor  stop- 
pages. There  is  no  distance  to  glide.  Hence 
they  must  fall. 

Whether  the  biplane  is  a  better  type  of  ma- 
chine than  the  monoplane,  it  would  be  difficult, 
if  not  impossible,  to  maintain.  It  is  certain, 
however,  that  the  biplane  has  been  brought  to 
a  higher  state  of  perfection  than  the  mono- 
plane, probably  because  it  was  the  first  success- 
ful type  of  a  man-carrying,  motor-driven  flying- 


FLYING-MACHINE   TYPES        19 

machine.  The  older  the  type,  the  more  marked 
will  be  the  improvements  to  which  it  will  be 
subjected.  It  is  curious,  too,  that  most  of  the 
pioneer  aviators  have  been  advocates  of  the 
biplane  type.  Lilienthal  met  his  death  in  a 
biplane.  Chanute,  who  brilliantly  continued 
Lilienthal's  work,  and  the  Wright  Brothers 
brought  the  motorless  biplane  glider  to  its 
highest  pitch  of  perfection.  The  first  flight 
ever  made  by  a  man-carrying,  motor-driven 
machine  was  that  of  a  Wright  biplane.  Voisin, 
Curtiss,  and  Farman,  all  of  them  experienced 
designers,  have  performed  their  most  brilliant 
feats  in  designing  or  flying  biplanes. 

Chanute  made  many  experiments  with  glid- 
ing-machines having  more  than  two  superposed 
surfaces;  but  he  found  in  the  end  that  the  bi- 
plane type  was  most  satisfactory.  Despite  the 
lessons  to  be  learned  from  his  painstaking  ex- 
periments, inventors  have  not  been  wanting 
who  have  worked  on  the  three-deck  or  triplane 
principle.  One  of  these  is  Farman,  who  de- 
signed the  Farman-Voisin  three-decked  ma- 
chine. Others  are  A.  V.  Roe  in  England  and 
Vanniman  in  France.  Vanniman  and  Farman 


20    THE   NEW   ART   OF    FLYING 

have  since  abandoned  their  triplane  structures, 
and  thus  rather  confirmed  Chanute's  conclu- 
sions. It  is  interesting  to  know  that  the  tri- 
plane goes  back  as  far  as  1868,  in  which  year 
an  inventor  named  Stringfellow  built  a  three- 
decked  model. 

The  many-planed  flying-machine  was  prob- 
ably carried  to  its  extreme  by  an  Englishman, 
Mr.  Horatio  Phillips.  Between  1881  and 
1894  he  made  a  series  of  experiments  which 
resulted  in  his  building  a  multiplane,  not  un- 
like a  Venetian  blind  in  appearance.  It  con- 
sisted primarily  of  a  series  of  numerous  super- 
posed slats,  which  had  extraordinary  lifting 
power.  Perhaps  the  chief  objections  to  such  a 
multiplane  are  its  weight  and  its  height.  Con- 
sequently it  is  less  stable  in  the  air  than  biplanes. 

Since  an  aeroplane,  whether  it  be  of  single- 
deck  or  double-deck  construction,  must  be 
driven  at  considerable  speed  to  keep  it  in  the 
air,  and  must,  furthermore,  get  up  a  certain 
preliminary  speed  before  it  can  fly  at  all,  some 
inventors  have  thought  of  rotating  the  planes, 
as  if  they  were  huge  propellers,  instead  of  driv- 
ing them  along  in  a  straight  line.  Such  screw- 


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FLYING-MACHINE   TYPES       21 

propellers,  to  push  a  machine  from  the  ground, 
are  mounted  on  a  vertical  shaft,  the  whole  con- 
stituting a  machine  which  goes  by  the  name 
"  helicopter."  A  helicopter  should  theoretically 
screw  its  way  up  into  the  air.  Because  no  screw- 
propeller  can  possibly  support  a  weight  in  air 
with  anything  like  the  aeroplane's  economy  of 
power,  the  helicopter  has  never  been  a  practical 
success.  In  a  helicopter,  the  screw-propeller 
must  be  designed  not  only  for  propulsion  but 
for  support  as  well.  As  far  back  as  1812  Pon- 
ton d'Amecourt  and  de  la  Landelle  maintained 
that  the  heavier-than-air  machine  would  be  sup- 
ported by  a  screw,  —  the  "  sacred  screw,"  to 
use  d'Amecourt's  ecstatic  Gallic  phrase.  They 
found  in  the  Academician  Babinet  a  stout  sup- 
porter of  their  view,  and  he  it  was  who  invented 
the  term  "  helicoptere."  The  familiar  little 
screw-fliers  which  are  whirled  into  the  air  by 
hand  or  by  twisted  rubber  bands  seemed  to  offer 
experimental  evidence  enough  in  support  of  any 
helicopter  theories.  It  was  recognised,  how- 
ever, that  one  screw  would  cause  the  entire 
apparatus  to  rotate.  Hence  two  screws  turning 
in  opposite  directions  were  early  recommended. 


22    THE    NEW   ART    OF    FLYING 

Thus  the  rotating  effect  of  one  screw  was  coun- 
teracted by  the  other,  and  the  lifting  effects  of 
the  two  were  combined. 

The  most  earnest  student  of  the  problem  of 
the  lifting  screw-flier  or  helicopter  has  been 
Colonel  Renard,  of  the  French  Army.  It  was 
he  who  first  pointed  out  in  1903  that  the  ordi- 
nary screw  would  not  answer.  A  helicopter's 
screw  must  not  only  propel,  but  must  also  sup- 
port, for  which  reason  it  must  be  differently 
constructed  from  a  screw  designed  for  propul- 
sion only.  Renard  even  went  so  far  as  to  plan 
a  composite  machine,  an  apparatus  which  was 
a  helicopter  for  lifting  itself  from  the  ground 
and  an  aeroplane  in  the  air.  Thus  he  hoped 
to  overcome  the  necessity  of  that  preliminary 
run  which  aeroplanes  must  make  in  order  that 
they  may  be  launched  in  the  air.  His  ma- 
chine would  theoretically  leap  straight  up  from 
the  ground. 

The  pathway  of  aeronautic  invention  is 
strewn  with  wrecked  helicopters.  Men  just 
as  distinguished  as  Renard  have  pinned  their 
faith  to  the  blades  of  its  revolving  screws. 
Among  them  have  been  Thomas  A.  Edison 


FLYING-MACHINE   TYPES        23 

and  Emil  Berliner.  Yet  the  only  perfectly 
operative  screw-flier  constructed  on  the  lifting- 
screw  principle  is  the  little  toy  to  which  ref- 
erence has  been  made.  In  France,  where 
fashions  in  aeroplanes  are  created  with  the 
same  facility  as  fashions  in  clothes,  the  heli- 
copter still  engages  the  attention  of  a  few  en- 
thusiasts, despite  the  brilliant  success  of  the 
aeroplane.  Cornu  is  one  of  these.  His  ma- 
chine undoubtedly  lifts;  but  thus  far  it  has 
not  been  allowed  to  display  its  capabilities  in 
that  direction  more  than  two  feet  from  the 
ground.  Breguet,  the  inventor  of  a  helicopter 
aeroplane,  is  said  to  have  flown  in  1908  a  dis- 
tance of  sixty-four  feet  at  a  height  of  fifteen 
feet.  He  is  now  building  aeroplanes. 

Even  less  encouraging  than  these  experi- 
ments with  helicopters,  have  been  the  efforts 
of  a  few  misguided  aviators  who  have  sought 
to  build  what  are  known  as  ornithopters  — 
machines  that  flap  wings  like  a  sparrow.  It 
seems  very  natural  to  adopt  the  flapping-wing 
principle,  because  all  birds  depend  upon  it  to 
a  certain  extent.  Apart  from  the  myth  of 
Daedalus  the  earliest  recorded  proposal  of 


24    THE    NEW   ART    OF    FLYING 

this  kind  was  made  in  1500,  by  Leonardo  da 
Vinci,  but  he  does  not  seem  to  have  made  a 
practical    test.      The    first    actual    experiment 
with    flapping    wings,    according    to    tradition, 
seems  to  have  been  made  by  a  French  tight- 
rope  dancer   named  A'llard,    in   the   reign   of 
Louis  XIV.     Allard  attempted  a  demonstra- 
tion before  the  court  but  failed  in  his  strength, 
fell,  and  was  seriously  hurt.     Since  that  time 
many    aviators    in    ornithopters    have    broken 
their  wings  and  sometimes  their  bones.     The 
most  earnest  experimenter  was  Hargrave,  who 
ultimately  gave  the  world  the  box-kite,  the  pro- 
totype of  the  biplane.     He  built  eighteen  flap- 
ping-wing   models    between    1883    and    1893. 
With  one  of  these  at  least,  a  flight  of  three 
hundred    and    forty-three    feet   was    made    in 
1891.     It  must  be  said  that  Hargrave  relied 
on   flapping  wings   solely   for  propulsion   and 
not   for   support.      His    efforts   to    devise    an 
efficient   sustaining   surface   gave   us   his   box- 
kite.     Only  a  few  French  inventors  still  per- 
sist in  working  on  the  ornithopter  principle. 
The  most  persistent  of  these   is  Adh.   de  la 
Hault.     His  machine,  exhibited  at  Brussels  in 


FLYING-MACHINE   TYPES        25 

1908,  has  wings  that  describe,  when  in  motion, 
a  figure-of-eight  curve.  His  results  have  been 
meagre. 

In  order  to  build  a  flying-machine  with  flap- 
ping wings,  so  as  to  imitate  birds  exactly,  a  very 
complicated  system  of  levers,  cams,  cranks,  and 
links  must  be  employed,  all  of  which  usually 
weigh  more  than  the  wings  can  lift. 


CHAPTER   III 

THE    PLANE   IN   THE   AIR 

A  ROWBOAT,  a  mud-scow,  a  battleship,  and  a 
racing  yacht,  whatever  aesthetic  differences  they 
may  present,  are  roughly  similar  in  form.  The 
swifter  the  vessel  the  finer  will  be  the  lines  of 
its  hull.  Naval  architects  after  some  centuries 
of  experimenting  have  laid  down  certain  rules 
of  construction  to  be  followed  in  building  ves- 
sels of  a  certain  class. 

The  plane  surface  is  to  the  aeroplane  what 
a  hull  is  to  a  ship.  Like  a  ship's  hull  it  must 
be  fashioned  to  cleave  the  medium  through 
which  it  must  travel  with  the  least  possible 
resistance.  Aeronautical  engineers  have  not 
solved  that  problem  entirely  as  yet,  for  the 
simple  reason  that  flying  has  only  recently  be- 
come an  assured  fact.  But  their  experiments 
have  given  them  certain  standards  which  they 
invariably  follow  when  they  design  an  aero- 
plane. Young  as  the  art  of  flying  is,  it  may 
well  be  questioned  whether  the  aeronautical  en- 


THE    PLANE    IN    THE   AIR       27 

gineer  is  not  in  possession  of  a  set  of  empirical 
formulae  almost  as  good  as  those  of  the  naval 
architect. 

.So  far  as  the  manner  of  cleaving  their  re- 
spective media  is  concerned,  there  is  this  im- 
portant difference  between  ships  and  planes :  — 
A  vessel  is  propelled  through  the  water  along 
the  line  of  least  resistance,  the  line  of  its  length; 
an  aeroplane,  whether  it  be  a  bird  or  a  Wright 
biplane,  is  driven  through  the  air  at  right 
angles  to  the  line  of  greatest  length  or 
resistance. 

What  is  known  as  the  "  entering  edge  "  of 
an  aeroplane,  in  other  words  the  character  of 
the  cutting  part  of  a  plane,  gives  the  aero- 
nautical engineer  much  concern.  It  is  the  enter- 
ing edge  that  strikes  the  air  first.  The  lifting- 
power  of  a  plane  gradually  dwindles  from  the 
entering  edge  backward.  A  plane  one  hundred 
feet  long  and  one  foot  wide  has  greater  lifting 
power  than  a  plane  ten  feet  square,  although 
both  planes  have  exactly  the  same  amount  of 
surface.  That  explains  why  the  wings  of  a 
bird  are  longer  in  span  than  in  width,  and  why 
the  aeroplanes  of  man  are  as  long  and  as  nar- 


28     THE    NEW   ART    OF    FLYING 

row  as  possible.  If  the  entire  surface  of  a  plane 
were  struck  by  the  air,  it  would  be  just  as  ad- 
vantageous to  employ  square  planes.  But  since 
the  air  bears  directly  only  on  the  front  or  enter- 
ing edge,  we  must  adopt  planes  that  give  us 


FIG.  7.  —  CD  is  the  "  entering  edge."  The  lifting  power  of 
the  forward  half  A  of  the  curved  plane  is  greater  than 
the  lifting  power  of  the  rear  half  B,  although  both  are 
of  equal  area. 

as  great  an  entering  edge  as  possible  without 
making  the  plane  too  unwieldy. 

Otto  Lilienthal  demonstrated,  after  much 
experiment,  that  if  an  oblong  surface  were 
curved,  the  loss  in  power  in  the  rear  half  of  a 
plane  might  be  overcome.  The  investigations 
of  others,  notably  Horatio  Phillips,  Prof.  S.  P. 
Langley,  Sir  Hiram  Maxim,  and  the  Wright 
Brothers,  have  confirmed  his  opinion.  Hence, 
despite  their  name,  the  best  aeroplanes  of  to- 


THE    PLANE    IN    THE   AIR       29 

day  are  made  not  with  flat,  but  with  surfaces 
slightly  curved  from  front  to  rear  (Fig.  7),  so 
that  the  rear  part  of  a  plane  can  "  grip  "  the 
air  almost  as  well  as  the  entering  edge.  De- 


B 


FIG.  8  —  A  is  a  simple  inclined  plane;  B,  a  curved  plane  at 
the  same  angle  of  incidence  or  inclination;  C,  the  type 
of  curved  plane  which  has  thus  far  given  the  best  results 
in  the  air. 

spite  the  curvature,  however,  there  is  an  ap- 
preciable loss  in  lifting  power,  back  of  the 
entering  edge. 

The  general  shape  which  a  plane  should  have 
must  be  considered  as  well  as  the  entering 
edge.  Much  experimental  research  has  shown 
that  the  best  plane  is  not  only  curved  back  and 


30    THE    NEW   ART    OF    FLYING 

down,  but  is  also  convex  on  top.  What  is  more, 
it  has  been  found  that  it  should  be  somewhat 
thicker  nearer  the  front.  Just  where  the  thick- 
est part  should  lie  is  still  a  matter  of  doubt; 
but  most  designers  place  the  thickest  part  at  a 
distance  from  the  front  edge  not  more  than 
a  third  of  the  total  width  of  the  plane  (Fig.  8) . 
A  kite  must  be  held  at  an  angle  to  the  wind 
if  it  is  to  fly.  So  must  an  aeroplane.  Just  what 
that  angle  should  be  varies  with  the  circum- 
stances of  flight.  The  flatter  the  angle  (in 
other  words,  the  more  horizontal  the  position 
of  the  aeroplane)  the  speedier  will  be  the  fly- 
ing-machine. The  greater  the  angle  of  the 
plane,  the  greater  will  be  the  resistance  offered 
and  the  greater  will  be  the  power  required  to 
drive  the  plane.  Still,  this  greater  angle  will 
enable  the  flying-machine  to  rise  more  quickly 
in  the  air,  because  the  lifting  power  is  greater. 
It  is  easy  to  see  that  the  aviator  must  select  such 
an  angle  for  his  planes  that  his  machine  will  be 
as  speedy  as  possible,  as  economical  of  power 
as  possible,  and  that  it  will  have  as  much  lifting 
power  as  possible.  The  angle  in  practical  flying- 
machines  varies  usually  from  one  in  seven  to 


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THE    PLANE    IN    THE   AIR       31 

one  in  twenty.  What  does  that  mean?  It 
means  that  a  plane  having  an  angle  of  one  in 
ten  will  push  the  air  down  at  one  tenth  of  the 
forward  velocity  and  that  the  plane  will  rise 
one  foot  in  ten  relatively  to  the  forward 
movement. 

An  aeroplane  driven  through  the  air  is  acted 
upon  by  two  forces,  —  its  weight  and  its  hori- 
zontal momentum.  Because  it  has  weight  it 
is  always  falling.  If  its  horizontal  momentum 
(its  speed)  is  greater  than  the  rate  of  its  fall, 
it  will  stay  in  the  air,  which  means  not  only  that 
it  has  not  time  enough  to  fall  visibly  but  that 
it  may  even  ascend.  Suppose  that  a  plane  trav- 
elling at  the  rate  of  ten  miles  an  hour  has  just 
sufficient  horizontal  momentum  to  prevent  its 
falling.  If  the  speed  be  increased  to  twenty 
miles  an  hour,  the  plane  will  not  only  be  pre- 
vented from  falling,  but  will  actually  rise  in  the 
air,  because  of  the  plane's  angle  of  inclination. 
Hence  to  prevent  the  plane  from  rising  at  a 
speed  of  twenty  miles  an  hour,  the  angle  must 
be  flattened.  Therefore  substantially  horizon- 
tal flight  may  be  maintained  by  proper  adjust- 
ment of  speed  and  angle  (Fig.  9). 


32    THE    NEW   ART    OF    FLYING 

The  angle  of  incidence  varies  with  the  wind, 
with  the  power  of  the  motor,  with  every  devia- 
tion of  the  plane  from  a  uniform  line,  and  with 
every  variation  of  the  load.  If  a  machine  car- 
ries two  men,  the  angle  will  be  greater  than  if 


E  D 

FIG.  9.  —  The  plane  B  B  is  at  a  greater  angle  of  incidence 
than  the  plane  A  A.  If  its  speed  be  10  miles  an  hour,  it 
will,  while  travelling  horizontally  25  feet,  overcome  its 
tendency  to  fall  to  D.  If  its  speed  be  20  miles  an  hour, 
it  will  have  50  feet  to  travel  while  overcoming  its  ten- 
dency to  fall  to  E.  Unless  the  angle  of  B  B,  therefore, 
were  decreased  to  that  of  A  A  for  the  greater  speed,  the 
plane  would  not  move  horizontally  but  would  ascend. 

one  is  carried;  when  the  fuel  tank  is  full  the 
angle  will  be  greater  than  when  the  tank  is 
empty,  and  will  vary  as  the  fuel  is  used.  More- 
over, when  the  power  of  the  motor  increases  or 
decreases,  the  speed  correspondingly  increases 
or  decreases  and  causes  the  angle  of  incidence 
to  increase  or  decrease.  Even  with  constant- 
power,  the  speed  is  different  in  ascending  and 


THE    PLANE    IN    THE   AIR       33 

descending,  and  the  angle  of  incidence  varies 
accordingly.  The  Wright  Brothers  state  that 
during  a  flight  of  one  hour  the  angle  of  inci- 
dence will  be  either  greater  or  less  than  any 
angle  which  may  be  termed  normal,  for  more 
than  fifty-nine  minutes,  and  that  it  will  be  ex- 
actly at  the  normal  angle  less  than  one  minute. 
In  their  experience  the  angle  of  incidence  varies 
in  flight  throughout  a  range  of  ten  degrees 
or  more  and  is  particularly  great  when  the 
wind  is  turbulent.  For  that  reason,  among 
others,  the  control  of  an  aeroplane  in  flight 
requires  incessant  vigilance  on  the  part  of  the 
pilot. 

In  most  forms  of  locomotion,  increased  speed 
is  obtained  at  the  expense  of  power.  When  you 
run,  you  expend  more  energy  than  when  you 
walk.  A  locomotive  driven  at  high  speed  uti- 
lises more  power  than  at  low  speed.  Paradoxi- 
cally enough,  the  aeroplane  follows  no  such 
rule.  The  late  Professor  Langley  discovered 
that  the  higher  the  speed  of  an  aeroplane,  the 
less  power  is  required  to  drive  it.  Langley 
was  considering  surfaces  only.  Wires  and 
struts  must  also  be  considered,  and  their  re- 


34    THE    NEW    ART    OF    FLYING 

sistance  (increasing  with  the  square  of  the 
velocity)  is  such  that,  as  Herring  has  pointed 
out,  flight  without  motor  is  impossible  on  ac- 
count of  the  resistance  offered  by  wires  alone. 
Theoretically  at  least,  it  seemed  to  Langley 
that  a  speed  could  be  reached  where  the  power 
received  would  be  nil.  The  Wrights  and  other 
aviators  maintain,  however,  that  there  is  a 
close  limit  to  this  economy  of  power  with  ac- 
celerated speed.  The  early  experiments  of 
Langley,  Maxim  and  Chanute  seemed  to  show 
that  at  high  speed  increased  lifting  power  is 
obtained,  but  how  much  the  increase  may 
be  not  all  the  experimenters  agree.  Con- 
trary, to  the  early  experimenters,  the  Wright 
Brothers  maintain  that  there  is  no  practical 
advantage  in  increasing  speed  to  obtain  in- 
creased lifting  power.  High  speed  renders  it 
possible  to  reduce  the  size  and  weight  of  the 
machine,  which  in  turn  means  a  reduction  in 
atmospheric  resistance. 

The  first  glimpse  of  a  flying-machine  in  the 
air  is  a  disappointment,  not  because  the  flying- 
machine  really  flies,  but  because  it  apparently 
flies  so  slowly.  The  speed  appears  less  than 


THE    PLANE    IN   THE   AIR       35 

it  really  is,  and  it  is  only  when  it  is  accurately 
measured  that  it  reaches  the  hoped-for  figure. 
The  speed  of  many  of  the  early  biplanes  was 
not  much  above  thirty  miles  an  hour,  and  most 
of  the  modern  biplanes  probably  do  not  exceed 
forty  miles.  Monoplanes  now  travel  often  at 
a  speed  of  not  less  than  sixty  miles.  Many  of 
the  Bleriot  monoplanes  make  considerably  over 
seventy  miles  an  hour  on  a  straight  line.  At 
Reims,  in  1910,  over  seventy  miles  an  hour  was 
attained.  It  is  evident  that  in  the  near  future 
eighty  miles  an  hour  on  a  straight  course  is 
well  within  the  bounds  of  probability. 

In  an  aeroplane  speed  is  of  more  importance 
than  any  other  vehicle,  because  the  aeroplane 
is  far  more  affected  by  the  wind.  A  boat,  to 
be  sure,  is  affected  by  both  tide  and  wind,  but 
not  to  such  an  extent  as  the  aeroplane.  A 
strong  tide  runs  only  about  two  knots,  while 
the  speed  of  a  fast  boat  is  some  ten  times  this, 
so  that  her  speed  is  reduced  only  ten  per  cent 
when  running  against  the  tide.  An  aeroplane, 
however,  is  very  much  more  influenced,  simply 
because  an  ordinary  breeze  has  a  velocity  of 
fifteen  miles  an  hour,  a  strong  wind  thirty  to 


36    THE    NEW   ART   OF    FLYING 

forty  miles  an  hour,  and  a  gale,  sixty  miles  an 
hour.  The  aeroplane,  in  order  to  be  a  service- 
able vehicle  of  sport,  must  be  able  to  make 
good  speed  against  a  thirty-mile  wind.  In 
other  words,  it  should  be  able  to  obtain  a  ve- 
locity of  sixty  or  seventy  miles  an  hour,  under 
favourable  conditions.  Such  fast  flying,  how- 
ever, complicates  the  problem  of  starting  and 
alighting.  Landing  at  high  speed  is  especially 
dangerous.  As  long  as  the  method  of  alight- 
ing is  what  it  is  now,  that  is,  as  long  as  the 
machine  runs  along  the  ground  for  some  dis- 
tance, it  can  hardly  be  safe  to  land  at  speeds 
in  excess  of  those  used  at  present.  It  is  evi- 
dent, therefore,  that  it  may  be  necessary  to 
devise  a  machine  which  will  fly  over  a  consider- 
able range  of  speed,  so  that  it  can  be  slowed 
down  before  landing.  The  minimum  speed  at 
which  an  aeroplane  will  fly  is  dependent  chiefly 
on  the  ratio  of  wing  surface  to  weight.  There- 
fore, to  fly  slowly  we  must  have  large  wings 
in  proportion  to  the  weight.  Small  wings,  on 
the  other  hand,  give  high  speed,  and  the  small 
wings  on  Bleriot  and  Wright  racers  seem  to 
be  very  small  indeed. 


THE    PLANE    IN    THE   AIR       37 

In  order  that  the  aeroplane  may  have  a  vari- 
able speed,  it  must  either  have  large  wings,  so 
designed  that  they  can  be  driven  fast  without, 
resistance,  or  else  we  must  have  some  me^ns 
of  reducing  the  surface  of  the  wings  in  the  air. 
In  the  former  case,  the  angle  of  incidence  of 
the  wings  is  reduced,  which  would  seem  to  be 
at  least  theoretically  obtainable,  whatever  may 
be  the  difficulties  in  making  the  curves  of  the 
wings  suitable  for  various  speeds. 

Reefing  the  wing  surfaces  is  a  still  better 
method  of  obtaining  variable  speeds,  but  the 
practical  difficulties  are  formidable.  Furling  a 
wing  when  travelling  at  forty  miles  an  hour  in 
the  air  can  hardly  be  easy.  Taking  in  sail  in 
a  gale  of  wind  on  a  boat  has  its  difficulties, 
and  an  aeroplane  travels  at  the  speed  of  a 
gale.  For  all  that,  we  find  that  attempts  are 
made,  even  now,  to  build  machines  on  this 
principle. 

Before  we  can  advance  much  farther  in  aero- 
plane construction  we  must  conduct  more  sys- 
tematic investigations  of  various  kinds  of  sup- 
porting surfaces.  Several  laboratories  are  now 
engaged  in  such  researches,  but  the  results  of 


38     THE    NEW   ART    OF    FLYING 

their  labours  will  hardly  be  available  for  some 
years  to  come. 

It  is  the  general  practice  of  ship-builders 
to  test  new  forms  of  hulls  by  towing  models  of 
a  few  yards  in  length  through  the  water  and  by 
measuring  the  resistance  opposed  to  their  mo- 
tion. No  large  ocean  steamer  is  now  con- 
structed without  such  preliminary  experiments. 
Tests  with  aeroplane  models  are  still  more 
necessary,  because  in  the  air  we  are,  as  yet, 
more  or  less  inexperienced.  In  both  cases  one 
of  the  chief  objects  of  study  is  the  total  resist- 
ance to  motion,  and  the  discovery  of  the  form 
which  will  reduce  this  resistance  to  the  lowest 
possible  point.  Other  important  questions  con- 
cern the  distribution  of  pressure  and  skin  fric- 
tion in  their  dependence  upon  the  form  and 
character  of  surface.  The  investigation  of  sta- 
bility and  steering  qualities  also  requires  ex- 
periments with  models,  which  may  likewise 
give  interesting  information  on  the  lifting 
power  or  kite  action  of  an  aeroplane  when 
inclined  to  the  horizontal.  It  is  necessary  to 
study  thoroughly  the  magnitude  and  direction 
of  the  resultant  force  on  single  surfaces  of 


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THE    PLANE    IN    THE   AIR       39 

various  forms,  on  combinations  of  surfaces, 
and  finally  on  complete  aeroplanes,  as  well  as 
the  stability  and  steering  qualities  of  these  com- 
binations. It  is  easier  and  cheaper  to  learn  from 
models  all  that  they  can  teach  us  than  to  make 
the  experiments  with  large  and  expensive  craft, 
which  has  been  the  practice  in  the  past.  It  is 
a  question,  however,  how  far  the  results  ob- 
tained from  models  can  be  applied  to  the  large 
vessels.  Even  small  models  of  ships'  hulls, 
which  are  tested  in  towing  tanks,  do  not  give 
absolute  results.  In  aeroplanes,  the  method 
may  be  still  more  untrustworthy  because  the 
aerial  craft  is  completely  surrounded  by  the 
medium  through  which  it  travels  and  because 
the  carriage  generally  creates  more  disturbance 
in  the  air  than  the  model,  a  disturbance  suffi- 
ciently great  to  make  exact  measurements  im- 
possible. By  substituting  for  the  towing  car- 
riage a  cord  wound  on  a  windlass,  this  objec- 
tion is  removed,  but  it  remains  very  difficult  to 
distinguish  sharply  between  the  comparatively 
small  air  resistances  and  the  great  force  of 
inertia  of  the  heavy  model.  M.  Eiffel  has  made 
some  excellent  experiments  with  bodies  freely 


40    THE    NEW   ART   OF    FLYING 

falling    through    the    air.      The    method    fre- 
quently employed  of  carrying  the  model  around 
in  a  circle  by  means  of  a  long  rotating  arm, 
or  on  a  whirling  table,  is  open  to  the  objec- 
tion that  the  model  is  always  moving  in  air 
which  has  been  disturbed  by  its  last  passage. 
There  is  still  a  third  method,  which  consists 
in  maintaining  the  model  at  rest  in  a  current 
of  air  produced,   for  example,   by   a  blower. 
The  mutual  action  between  the  model  and  the 
air  is  exactly  as  in  the  former  system,  if  the 
condition  of  the  moving  air  before  it  strikes 
the  model  is  as  uniform  as  that  of  still  air. 
The  trustworthiness  of  results  obtained  by  this 
method  depends,  therefore,  upon  obtaining  a 
uniform  current  free  from  eddies,  which  end 
can  be  attained  by  the  employment  of  various 
appliances.    When  a  uniform  current  has  been 
secured,   the   advantages   of   this   method   are 
great  and  obvious.     The  duration  of  the  ex- 
periment is  unlimited,   and  the  model  can  be 
attached  to  its  support  much  more  easily  and 
securely  than  if  it  were  in  motion.     Further- 
more, the  difficulties  produced  by  the  accelera- 
tion and  inertia  of  the  model  on  a  measuring 


THE   PLANE   IN   THE  AIR      41 

apparatus  are  here  avoided.  The  model  is 
continuously  in  sight,  so  that  any  irregularities 
can  be  at  once  detected.  This  system  has  been 
adopted  in  the  Goettingen  Experimental  Insti- 
tute, planned  and  directed  by  Professor  Prandtl. 


CHAPTER   IV 

STARTING  AND  ALIGHTING 

IN  a  previous  chapter  it  has  been  pointed  out 
that  like  every  soaring  bird  an  aeroplane  must 
be  in  motion  before  it  can  fly.  Even  the  early 
dreamers  appreciated  the  fact.  How  that  pre- 
liminary leap  into  the  air  is  to  be  effected  gave 
Langley  no  little  concern.  With  the  motorless 
gliders  of  Lilienthal,  Pilcher,  and  Chanute,  it 
was  no  difficult  matter  for  the  aeronaut  to 
launch  himself  into  the  air.  He  simply  carried 
his  apparatus  to  the  top  of  a  hill,  grasped  the 
handle-bar,  ran  down  the  hill  at  top  speed  for 
a  short  distance,  and  then  drew  up  his  legs,  like 
any  bird.  Thus  he  would  slide  down  the  air 
for  several  hundred  feet  as  if  upon  an  invisible 
track. 

When  Langley  succeeded  in  building  a  small, 
motor-driven  model  of  a  flying-machine,  the 
problem  of  launching  his  contrivance  long 
baffled  him.  Eventually  he  invented  a  launch- 
ing device,  which  has  served  as  a  pattern  for 


STARTING   AND   ALIGHTING     43 

later  inventors.  The  difficulties  which  beset 
him  were  eloquently  and  lucidly  described  in 
an  article  from  his  pen,  published  in  McClure's 
Magazine  for  June,  1897.  The  whole  prob- 
lem is  there  so  well  and  so  simply  presented 
that  we  cannot  do  better  than  to  let  Mr.  Lang- 
ley  set  it  forth  himself,  even  though  launching 
a  flying-machine  is  now  regarded  as  a  simple 
matter: 

"  In  the  course  of  my  experiments  I  had 
found  out  .  .  .  that  the  machine  must  begin 
to  fly  in  the  face  of  the  wind  and  just  in  the 
opposite  way  to  a  ship,  which  begins  its  voyage 
with  the  wind  behind  it. 

"  If  the  reader  has  ever  noticed  a  soaring 
bird  get  upon  the  wing  he  will  see  that  it  does 
so  with  the  breeze  against  it,  and  thus  when- 
ever the  aerodrome  *  is  cast  into  the  air  it  must 
face  a  wind  which  may  happen  to  blow  from 
the  north,  south,  east  or  west,  and  we  had 
better  not  make  the  launching  station  a  place 
like  the  bank  of  a  river,  where  it  can  go  only  one 
way.  It  was  necessary,  then,  to  send  it  from 
something  which  could  be  turned  in  any  direc- 
tion, and  taking  this  need  in  connection  with 

*  *  Langley's  term  for  an  aeroplane  flying-machine,  signifying 
"  air-runner." 


44    THE    NEW   ART    OF    FLYING 

the  desirability  that  at  first  the  airship  should 
light  in  the  water,  there  came  at  last  the  idea 
(which  seems  obvious  enough  when  it  is  stated) 
of  getting  some  kind  of  a  barge  or  boat  and 
building  a  small  structure  upon  it  which  could 
house  the  aerodrome  when  not  in  use,  and  from 
whose  flat  roof  it  could  be  launched  in  any 
direction.  Means  for  this  were  limited,  but  a 
little  "  scow "  was  procured,  and  on  it  was 
built  a  primitive  sort  of  house,  one  story  high, 
and  on  the  house  a  platform  about  ten  feet 
higher,  so  that  the  top  of  the  platform  was 
about  twenty  feet  from  the  water,  and  this 
was  to  be  the  place  of  the  launch.  This  boat  it 
was  found  necessary  to  take  down  the  river 
as  much  as  thirty  miles  from  Washington, 
where  I  then  was  —  since  no  suitable  place 
could  be  found  nearer  —  to  an  island  having 
a  stretch  of  quiet  water  between  it  and  the  main 
shore;  and  here  the  first  experiments  in  at- 
tempted flight  developed  difficulties  of  a  new 
kind  —  difficulties  which  were  partly  antici- 
pated, but  which  nobody  would  probably  have 
conjectured  would  be  of  their  actually  formi- 
dable character,  which  was  such  as  for  a  long 
time  to  prevent  any  trial  being  made  at  all. 
They  arose  partly  out  of  the  fact  that  even 
such  a  flying-machine  as  a  soaring  bird  has  to 
get  up  an  artificial  speed  before  it  is  on  the 


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STARTING    AND   ALIGHTING     45 

wing.  Some  soaring  birds  do  this  by  an  initial 
run  upon  the  ground,  and  even  under  the  most 
urgent  pressure  cannot  fly  without  it. 

uTo  get  up  this  preliminary  speed  many 
plans  were  proposed,  one  of  which  was  to  put 
the  aerodrome  on  the  deck  of  a  steamboat,  and 
go  faster  and  faster  until  the  head-wind  lifted 
it  off  the  deck.  This  sounds  reasonable,  but  it 
is  absolutely  impracticable,  for  when  the  aero- 
drome is  set  up  anywhere  in  the  open  air,  we 
find  that  the  very  slightest  wind  will  turn  it 
over,  unless  it  is  firmly  held.  The  whole  must 
be  in  motion,  but  in  motion  from  something  to 
which  it  is  held  until  that  critical  instant  when 
it  is  set  free  as  it  springs  into  the  air. 

"  The  house  boat  was  fitted  with  an  appara- 
tus for  launching  the  aerodrome  with  a  certain 
initial  velocity,  and  was  (in  1893)  taken  down 
the  river  and  moored  in  the  stretch  of  quiet 
water  I  have  mentioned;  and  it  was  here  that 
the  first  trials  at  launching  were  made,  under 
the  difficulties  to  which  I  have  alluded. 

"  It  is  a  difficult  thing  to  launch  a  ship,  al- 
though gravity  keeps  it  down  upon  the  ways, 
but  the  problem  here  is  that  of  launching  a  kind 
of  ship  which  is  as  ready  to  go  up  into  the  air 
like  a  balloon  as  to  go  off  sideways,  and  readier 
to  do  either  than  to  go  straight  forward,  as  it 
is  wanted  to  do,  for  though  there  is  no  gas  in 


46    THE    NEW   ART   OF    FLYING 

the  flying-machine,  its  great  extent  of  wing 
surface  renders  it  something  like  an  albatross 
on  a  ship's  deck  —  the  most  unmanageable  and 
helpless  of  creatures  until  it  is  in  its  proper 
element. 

"  If  there  were  an  absolute  calm,  which  never 
really  happens,  it  would  still  be  impracticable 
to  launch  it  as  a  ship  is  launched,  because  the 
wind  made  by  running  it  along  would  get  under 
the  wings  and  turn  it  over.  But  there  is  always 
more  or  less  wind,  and  even  the  gentlest  breeze 
was  afterward  found  to  make  the  airship  un- 
manageable unless  it  was  absolutely  clamped 
down  to  whatever  served  to  launch  it,  and  when 
it  was  thus  firmly  clamped,  as  it  must  be  at 
several  distinct  points,  it  was  necessary  that 
it  should  be  released  simultaneously  at  all  these 
at  the  one  critical  instant  that  it  was  leaping 
into  the  air.  This  is  another  difficult  condi- 
tion, but  that  it  is  an  indispensable  one  may  be 
inferred  from  what  has  been  said.  In  the  first 
form  of  launching  piece  this  initial  velocity  was 
sought  to  be  attained  by  a  spring,  which  threw 
forward  the  supporting  frame  on  which  the 
aerodrome  rested;  but  at  this  time  the  extreme 
susceptibility  of  the  whole  construction  to  in- 
jury from  the  wind  and  the  need  of  protecting 
it  from  even  the  gentlest  breeze  had  not  been 
appreciated  by  experience.  On  November  18, 


STARTING    AND   ALIGHTING    47 

1893,  the  aerodrome  had  been  taken  down  the 
river,  and  the  whole  day  was  spent  in  waiting 
for  a  calm,  as  the  machine  could  not  be  held  in 
position  for  launching  for  two  seconds  in  the 
lightest  breeze.  The  party  returned  to  Wash- 
ington and  came  down  again  on  the  2Oth,  and 
although  it  seemed  that  there  was  scarcely  any 
movement  in  the  air,  what  little  remained  was 
enough  to  make  it  impossible  to  maintain  the 
aerodrome  in  position.  It  was  let  go,  notwith- 
standing, and  a  portion  struck  against  the  edge 
of  the  launching  piece,  and  all  fell  into  the 
water  before  it  had  an  opportunity  to  fly. 

"  On  the  24th  another  trip  was  made  and 
another  day  spent  ineffectively  on  account  of 
the  wind.  On  the  zyth  there  was  a  similar 
experience,  and  here  four  days  and  four 
(round-trip)  journeys  of  sixty  miles  each  had 
been  spent  without  a  single  result.  This  may 
seem  to  be  a  trial  of  patience,  but  it  was  re- 
peated in  December,  when  five  fruitless  trips 
were  made,  and  thus  nine  such  trips  were  made 
in  these  two  months  and  but  once  was  the 
aerodrome  even  attempted  to  be  launched,  and 
this  attempt  was  attended  with  disaster.  The 
principal  cause  lay,  as  I  have  said,  in  the  un- 
recognised amount  of  difficulty  introduced  even 
by  the  very  smallest  wind,  as  a  breeze  of  three 
or  four  miles  an  hour,  hardly  perceptible  to  the 


48    THE    NEW   ART   OF    FLYING 

face,  was  enough  to  keep  the  airship  from  rest- 
ing in  place  for  the  critical  seconds  preceding 
the  launching. 

"  If  we  remember  that  this  is  all  irrespective 
of  the  fitness  of  the  launching  piece  itself,  which 
at  first  did  not  get  even  a  chance  for  trial,  some 
of  the  difficulties  may  be  better  understood; 
and  there  were  many  others. 

"  During  most  of  the  year  of  1894  there  was 
the  same  record  of  defeat.  Five  more  trial 
trips  were  made  in  the  spring  and  summer,  dur- 
ing which  various  forms  of  launching  apparatus 
were  tried  with  varied  forms  of  disaster.  Then 
it  was  sought  to  hold  the  aerodrome  out  over 
the  water  and  let  it  drop  from  the  greatest  at- 
tainable height,  with  the  hope  that  it  might  ac- 
quire the  requisite  speed  of  advance  before  the 
water  was  reached.  It  will  hardly  be  anticipated 
that  it  was  found  impracticable  at  first  to  simply 
let  it  drop  without  something  going  wrong,  but 
so  it  was,  and  it  soon  became  evident  that  even 
were  this  not  the  case,  a  far  greater  time  of  fall 
was  requisite  for  this  method  than  that  at  com- 
mand. The  result  was  that  in  all  these  eleven 
months  the  aerodrome  had  not  been  launched, 
owing  to  difficulties  which  seem  so  slight  that 
one  who  has  not  experienced  them  may  wonder 
at  the  trouble  they  caused. 


* 


I  I 


STARTING    AND   ALIGHTING    49 

"  Finally,  in  October,  1894,  an  entirely  new 
launching  apparatus  was  completed,  which  em- 
bodied the  dozen  or  more  requisites,  the  need 
for  which  had  been  independently  proved  in 
this  long  process  of  trial  and  error.  Among 
these  was  the  primary  one  that  it  was  capable 
of  sending  the  aerodrome  off  at  the  requisite 
initial  speed,  in  the  face  of  a  wind  from 
whichever  quarter  it  blew,  and  it  had  many 
more  facilities  which  practice  had  proved 
indispensable." 

Langley's  account  has  a  certain  historical 
interest,  because  never  before  had  a  motor- 
driven  machine  been  brought  to  such  a  pitch  of 
perfection  that  it  could  fly,  if  once  launched. 
After  his  repeated  failures,  Langley  finally 
succeeded  in  launching  his  craft  from  "  ways," 
as  shown  in  Fig.  n,  somewhat  as  a  ship  is 
launched  into  the  water,  the  machine  resting  on 
a  car,  which  fell  down  at  the  end  of  the  car's 
motion. 

A  launching  device  identical  in  principle  was 
afterwards  employed  to  start  the  man-carrying 
machine  built  by  Langley  for  the  United  States 
Government.  Once,  according  to  Major  Ma- 
comb,  of  the  Board  of  Ordnance,  u  the  trial  was 


50    THE   NEW   ART   OF    FLYING 

unsuccessful  because  the  front  guy  post  caught 
in  its  support  on  the  launching  car  and  was  not 
released  in  time  to  give  free  flight,  as  was  in- 
tended, but,  on  the  contrary,  caused  the  front 
of  the  machine  to  be  dragged  downward,  bend- 
ing the  guy  post  and  making  the  machine  plunge 
into  the  water  about  fifty  yards  in  front  of  the 
house  boat."  Of  another  trial  Major  Macomb 
states  .  .  .  "  the  car  was  set  in  motion  and  the 
propellers  revolved  rapidly,  the  engine  working 
perfectly,  but  there  was  something  wrong  with 
the  launching.  The  rear  guy  post  seemed  to 
drag,  bringing  the  rudder  down  on  the  launch- 
ing ways,  and  a  crashing,  rending  sound,  fol- 
lowed by  the  collapse  of  the  rear  wings,  showed 
that  the  machine  had  been  wrecked  •  in  the 
launching;  just  how  it  was  impossible  to  see.'* 
Because  it  was  never  launched,  the  machine 
never  flew.  The  appropriation  having  been 
exhausted,  Langley  was  compelled  to  abandon 
his  tests.  The  newspaper  derision  which 
greeted  him  undoubtedly  embittered  him,  short- 
ened his  life,  and  probably  set  back  the  date 
of  the  man-carrying  flying-machine's  advent 
several  years.  Langley's  trials  have  been  here 


STARTING   AND   ALIGHTING     51 

set  down  at  some  length  to  show  the  practica- 
bility and  impracticability  of  various  launching 
methods  and  to  demonstrate  that  his  machine 
was  far  from  being  the  failure  popularly  sup- 
posed. No  man  has  contributed  so  much  to 
the  science  of  aviation  as  the  late  Samuel  Pier- 
pont  Langley. 

That  his  work  was  not  lost  on  the  Wright 
Brothers  at  least,  is  evidenced  by  the  manner 
in  which  they  attacked  the  difficulty  of  getting 
up  starting  speed.  The  Wright  Brothers  in- 
vented an  arrangement,  which  was  simpler  than 
Langley's,  more  efficient,  and  not  so  likely  to 
imperil  the  aeroplane.  As  illustrated  in  Fig- 
ures 12  and  13,  it  consisted  in  its  early  stage 
of  an  inclined  rail,  about  seventy  feet  long;  a 
pyramidal  "  derrick " ;  a  heavy  weight  ar- 
ranged to  drop  within  the  derrick;  and  a  rope 
which  was  fastened  to  the  weight,  led  around 
a  pulley  at  the  top  of  the  derrick,  passed  around 
a  second  pulley  at  the  bottom  of  the  derrick 
and  over  a  third  pulley  at  the  end  of  the  rail, 
and  then  secured  to  a  car.  The  car  was  placed 
on  the  rail,  and  the  aeroplane  itself  on  the 
car.  When  a  trigger  was  pulled,  the  weight 


52    THE    NEW   ART    OF    FLYING 

fell,  and  the  car  was  jerked  forward.  So  great 
was  the  preliminary  velocity  thus  imparted 
that  the  machine  was  able  to  rise  from  the  car 
in  a  few  seconds. 


FIG.  12.  —  The  special  launching  device  invented  by  the 
Wright  Brothers.  The  device  consists  of  an  inclined 
rail,  about  seventy  feet  long;  a  pyramidal  derrick;  a 
heavy  weight  arranged  to  drop  within  the  derrick;  and 

[  a  rope,  which  is  fastened  to  the  weight,  passed  around 
a  pulley  at  the  top  of  the  derrick,  then  around  a 
second  pulley  at  the  bottom  of  the  derrick  over  a  third 
pulley  at  the  end  of  the  rail,  and  finally  fastened  to 
a  car  running  on  the  rail.  The  car  is  placed  on  the 
rail,  and  the  aeroplane  on  the  car.  When  a  trigger  is 
pulled,  the  weight  falls,  and  the  car  is  jerked  forward. 
So  great  is  the  preliminary  velocity  thus  imparted  that 
the  machine  is  able  to  rise  in  a  few  seconds  from  the 
car,  which  is  left  behind. 

Neither  a  falling  weight  nor  a  starting  car- 
riage on  rails  can  be  carried  with  an  aero- 
plane. Hence,  a  machine  thus  launched  must 
always  return  to  its  derrick.  Clearly,  an  aero- 
plane which  can  start  up  under  its  own  power 
is  preferable  to  one  which  is  wedded  to  a  start- 
ing derrick  or  any  other  extraneous  launching 


STARTING   AND   ALIGHTING     53 

apparatus.  Inasmuch  as  more  power  is  re- 
quired for  starting  by  running  on  the  ground 
(i.  e.,  for  accelerating  the  machine)  than  for 
actual  flight,  the  Wright  Brothers  continued  to 
employ  their  starting  rail  long  after  other  avi- 
ators had  adopted  wheels.  The  result  was  that 
they  could  equip  their  machine  with  motors  of 
far  less  power  than  their  rivals. 

Even  before  the  Wright  Brothers  threw 
aside  all  secrecy  and  flew  publicly  in  France 
and  the  United  States  during  the  summer  of 
1908,  Curtiss  and  Farman  had  made  short 
flights  on  machines  which  were  mounted  on 
pneumatic-tired  wheels.  Their  machines  would 
run  on  the  wheels  for  several  hundred  feet. 
When  sufficient  velocity  had  been  attained  the 
pilot  would  give  a  slight  upward  tilt  to  the  ele- 
vating rudder,  and  the  machine  would  leave 
the  ground.  The  only  essential  was  a  fairly 
smooth,  fairly  hard  piece  of  ground  for  the 
preliminary  run.  So  successful  has  this  system 
been  that  in  somewhat  improved  form  it  is 
embodied  in  every  modern  aeroplane.  Even 
the  Wright  Brothers,  who  long  persisted  in 
using  the  starting  derrick  in  the  face  of  the 


54    THE    NEW   ART    OF    FLYING 

obvious  advantages  of  wheels,  abandoned  the 
starting  derrick  as  soon  as  they  had  increased 
the  power  of  their  motors.  In  Fig.  14  one  of 
their  later  machines  is  pictured,  mounted  on 
wheels. 

Although  starting  wheels  enable  the  aviator 
to  rise  from  any  suitable  piece  of  ground,  he 
pays  for  that  advantage  in  engine  power.  A 
well-made  machine,  having  ample  power  to 
fly,  but  dependent  only  on  its  engine  and 
rubber-tired  wheels  for  its  initial  run,  may  be 
unable  to  rise  if  the  ground  is  too  rough.  The 
engine  cannot  overcome  the  loss  due  to  fric- 
tion. On  hard  asphalt  the  cyclist  can  readily 
attain  a  speed  of  twenty-five  miles  an  hour  in 
a  few  seconds;  on  a  ploughed  field,  he  may 
labour  hard  and  yet  not  make  more  than  ten 
miles  an  hour.  The  aeroplane  is  in  the  same 
position  as  the  bicycle.  To  start  a  flying- 
machine  on  rough  ground  requires  more  power 
than  is  afterwards  needed  for  propulsion. 
Hence  we  find  that  the  earlier  Wright  ma- 
chines, although  they  could  rise  only  from  the 
perfect  surface  of  a  starting  rail,  were  fitted 
with  engines  of  remarkably  low  power. 


Photograph  by  Edwin  Levick 

Fig.  20. — Mr.  Wilbur  Wright  in  the  old  type 
Wright  biplane 


STARTING   AND   ALIGHTING     55 

The  wheels  on  which  the  preliminary  run  is 
made  may  also  serve  the  aviator  in  alighting. 
After  he  shuts  off  his  engine  he  glides  down 
and  runs  on  the  wheels  until  his  momentum  is 
expended.  The  shock  may  be  sufficient  to 
wreck  a  machine  piloted  by  an  unskilled  hand, 
and  the  run  may  be  long,  unless  some  form  of 
brake  is  provided.  Recognising  these  disad- 
vantages early  in  the  course  of  their  experi- 
ments, the  Wright  Brothers  fitted  their  aero- 
planes with  skids  or  runners  on  which  the 
machine  alighted.  The  shock  is  almost  im- 
perceptible, and  the  machine  stops  in  the  course 
of  a  few  yards  without  the  assistance  of  a 
brake.  Many  machines  are  now  equipped  with 
skids  similar  to  those  embodied  long  ago  by 
Herring  and  by  the  Wright  Brothers  in  their 
early  models. 

Starting  wheels  and  alighting  skids  are  not 
easily  combined  in  the  same  machine.  The 
skids  must  be  elevated  sufficiently  to  clear  the 
ground  in  making  the  preliminary  run,  and  yet 
they  must  become  effective  as  soon  as  the  ma- 
chine touches  the  ground.  For  that  reason  the 
wheels  are  usually  connected  with  springs, 


56    THE   NEW   ART   OF    FLYING 

which  are  compressed  as  the  aeroplane  strikes 
the  ground  so  as  to  allow  the  skids  to  perform 
the  function  for  which  they  are  designed. 

In  the  Farman  biplane,  for  example,  the 
wheels  are  mounted  on  the  skids  and  are  at- 
tached to  rubber  springs.  When  the  machine 
alights  the  wheels  yield,  and  the  skids  come  into 
play. 

In  the  Sommer  biplane,  the  framework  is 
carried  on  two  large  wheels  at  the  front  and 
two  smaller  wheels  at  the  rear.  The  front 
wheels  are  attached  by  rubber  springs  to  two 
skids,  built  under  the  frame.  As  in  the  Farman 
machine,  the  wheels  yield  by  virtue  of  this 
spring  mounting. 

In  Santos-Dumont's  monoplane  "  Demoi- 
selle," springs  are  dispensed  with.  The  ma- 
chine starts  on  two  wheels  in  front  and  the 
shock  of  alighting  is  broken  by  a  skid  at  the 
rear. 

An  arrangement  similar  to  that  of  Santos- 
Dumont  is  to  be  found  in  the  Antoinette  ma- 
chines. The  mounting  consists  of  two  wheels 
at  the  front  and  a  skid  at  the  rear.  No  springs 
are  provided  for  the  wheels. 


STARTING   AND   ALIGHTING     57 

In  the  Curtiss  and  Voisin  biplane  machines, 
as  well  as  in  some  others  of  minor  importance, 
no  skids  at  all  are  employed.  The  machine 
starts  and  alights  on  the  same  set  of  wheels, 
and  is  usually  stopped  by  brakes.  On  the  whole 
the  combination  of  wheels  and  skids  seems  to 
be  more  desirable,  particularly  for  a  heavy 
machine. 


CHAPTER   V 

HOW  AN  AEROPLANE   IS   BALANCED 

DROP  a  flat  piece  of  cardboard  from  your  hand. 
It  will  fall.  But  as  it  falls  its  surface  will  offer 
a  certain  resistance,  so  that  it  becomes  in  effect 
a  parachute.  The  amount  of  its  resistance  will 


FIG.  16.  —  Path  of  an  aeroplane  driven  forward  but  with  a 
speed  too  low  for  horizontal  flight,  and  with  too  flat  an 
angle. 

depend  on  the  amount  of  its  surface.  If  the 
cardboard  be  driven  to  the  left,  as  shown  in 
Fig.  1 6,  it  will  still  fall,  but  along  an  inclined 
path.  In  other  words  it  will  fall  while  advanc- 
ing and  advance  while  falling. 

Suppose  that  this  same  piece  of  cardboard, 
this  aeroplane,  as  we  may  call  it,  is  inclined  to 


BALANCING   AEROPLANES       59 

the  wind  and  that  it  is  driven  along  a  horizontal 
path  B  in  the  direction  of  the  arrow  A  as  shown 
in  Fig.  17.  If  it  were  not  driven  forward  the 
cardboard  plane  would  fall  by  reason  of  its 
weight.  But  since  it  is  driven  forward  and  since 
it  is  inclined  to  the  air,  it  offers  resistance,  which 
means  that  pressure  is  exerted  upward  against 


Rear  Edge 


FIG.  17.  —  Path  of  a  plane  inclined  at  the  angle  C  to  the 
horizontal.  The  arrow  A  indicates  the  direction  of 
travel.  If  the  speed  is  sufficient  the  plane  will  rise  be- 
cause of  the  upward  inclination  of  the  plane. 

its  lower  surface.  The  driving  power,  what- 
ever it  may  be,  overcomes  the  resistance  or 
pressure;  yet  the  effect  of  the  resistance  or 
pressure  is  to  keep  the  plane  up  in  the  air.  So, 
the  plane  tends  to  slide  up  diagonally  on  the 
resisting  air;  gravity  (weight)  tends  to  draw 
the  plane  down  toward  the  earth;  and  the  diag- 
onal sliding  action  tends  to  move  the  plane 
farther  from  the  earth.  This  climbing  effect  is 
obviously  dependent  on  the  angle  of  the  plane. 


60    THE    NEW   ART    OF    FLYING 

If  the  angle  is  large,  it  is  great;  if  the  angle  is 
small,  it  is  slight.  Given  a  very  high  speed  of 
propulsion,  a  speed  greater  than  the  falling 
tendency,  and  the  plane  is  bound  to  rise.  Given 
a  speed  of  propulsion  less  than  the  falling  ten- 
dency and  the  plane  will  sooner  or  later  settle 
to  the  ground.  Horizontal  flight  can  therefore 
be  maintained  by  proper  adjustment  of  speed 
and  angle. 

This  angle  at  which  the  plane  moves  against 
the  air  is  known  as  the  "  angle  of  incidence." 
It  is  positive,  because  it  has  a  tendency  to  lift. 
If  the  plane  were  tilted  forward  or  dipped,  the 
sliding  effect  would  be  earthward.  Indeed,  so 
marked  would  be  this  effect  that  the  plane 
would  reach  the  ground  much  more  quickly  than 
if  it  fell  simply  by  its  own  weight.  In  that  case 
the  angle  of  incidence  is  negative,  because  it 
depresses. 

It  is  therefore  evident  that  an  advancing 
aeroplane  may  be  caused  to  travel  up  or  down 
simply  by  making  the  angle  of  incidence  posi- 
tive or  negative. 

During  flight,  a  Wright  or  Curtiss  or  Bleriot 
machine  is  subjected  to  every  whim  of  the  air. 


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BALANCING   AEROPLANES       61 

These  incessant  variations  of  the  air  must  all 
be  counteracted;  otherwise  the  machine  will 
capsize. 

It  happens  during  flight  that  the  aeroplane, 
because  of  the  wind's  caprice,  will  drop  more 
on  one  side  than  on  the  other.  To  maintain  his 
balance,  the  aviator  must  in  some  way  lift  the 
falling  side  or  lower  the  rising  side,  or  do  both. 
It  was  this  problem  that  long  baffled  the  in- 
ventor of  aeroplane  flying-machines.  The 
whole  art  of  machine-flying  is  summed  up  in  its 
successful  solution.  To  the  Wright  Brothers  of 
Dayton,  Ohio,  belongs  the  full  credit  of  having 
devised  the  first  and  thus  far  the  most  efficient 
means  of  solving  that  problem,  a  means  now  em- 
bodied in  almost  every  successful  flying-machine. 

Suppose  that  the  plane  A  in  Fig.  1 8  is  pro- 
vided at  each  side  with  tips  C  and  D,  hinged 
so  that  they  can  be  swung  up  or  down.  If  these 
two  tips  (ailerons  the  French  call  them)  are 
swung  so  that  they  lie  flush  with  the  main 
plane  A,  they  have  no  effect  whatever  beyond 
adding  to  the  amount  of  aeroplane  surface. 
Suppose  that  the  near  side  of  the  plane  drops. 
In  that  case,  the  tip  C  is  thrown  down  as  shown 


62    THE    NEW   ART   OF    FLYING 

in  Fig.  1 8.  What  happens?  More  resistance 
is  offered  to  the  air  at  that  side  and  greater 
upward  pressure  is  consequently  exerted,  so 
that  the  plane  is  restored  to  its  former  position 

Direction  of  Plane's  Motion 


Direction  of  Air  Pressure 


FIG.  18.  —  How  a  plane  is  laterally  balanced  by  means  of 
ailerons  and  a  vertical  rudder. 

The  plane  A  is  provided  with  hinged  tips  C  and  D  and  with 
a  vertical  rudder  E.  The  tips  are  swung  in  opposite 
directions  to  correct  any  tipping  of  the  plane,  and  the 
vertical  rudder  E  is  swung  over  to  the  side  of  least  re- 
sistance (the  side  of  the  tip  D  in  the  example  here  given) 
in  order  to  prevent  the  entire  machine  from  rotating  on 
a  vertical  axis. 

of  equilibrium.  To  assist  in  this  restoration, 
the  tip  D  at  the  farther  side  of  the  plane  can  be 
tilted  down,  so  that  the  angle  of  incidence  is 
negative  or  depressive.  Hence  the  far  end  of 
the  plane  is  lowered  while  the  near  end  is  raised. 
In  all  flying-machines  this  dropping  of  one  tip 
and  raising  of  the  other  is  effected  simultane- 
ously by  a  system  of  cables  and  levers.  When 


BALANCING   AEROPLANES       63 

the  plane's  balance  has  been  regained,  the  tips 
are  swung  so  that  they  lie  flush  with  the  plane 
A,  and  become  virtually  part  of  the  plane. 

As  a  result  of  inclining  the  tips  at  opposite 
angles,  the  near  side  of  the  plane  offers  more 
resistance  to  the  air  than  the  far  side.  Hence 
the  near  side  will  be  retarded  and  the  far  side 
accelerated.  This  will  cause  the  entire  plane 
to  swerve  from  its  course.  It  was  a  brilliant 
discovery  of  the  Wright  Brothers  to  correct  this 
swerving  by  means  of  a  vertical  rudder  E, 
which  is  thrown  over  to  the  side  of  least  resist- 
ance —  the  far  side  in  the  particular  instance 
pictured  in  Fig.  18.  The  wind  pressure  on  the 
rudder  exerts  a  counteracting  force  at  the  rear 
of  the  machine  and  opposes  the  tendency  of  the 
machine  to  turn.  Hence  the  vertical  rudder  in 
flying-machines  serves  not  nearly  so  much  for 
steering  as  for  preventing  the  spinning  of  the 
machine. 

The  actual  controlling  method  devised  by 
the  Wrights  is  shown  in  Fig.  19.  Instead  of 
one  plane,  the  Wrights  employ  two  superposed 
planes  A  and  A'  trussed  together.  In  front  or 
rear  is  a  horizontal  rudder  or  elevator  to  steer 


64  THE  NEW  ART  OF  FLYING 
the  machine  up  or  down,  which  rudder  in  the 
example  before  us  (an  old  Wright  type  al- 
though the  principle  is  the  same  in  the  new) 
consists  of  two  superposed  planes,  5  and  6, 
and  which  is  operated  by  the  lever  F'  through 
the  medium  of  connecting  rods.  In  the 


FIG.  19.  —  The  system  of  control  on  an  old  Wright  model. 

rear  is  the  vertical  rudder  C,  which  serves  to 
steer  the  machine  from  side  to  side  and  to  coact 
with  the  planes  A  and  A'  in  keeping  the  ma- 
chine on  its  course.  Instead  of  employing 
pivoted  tips  like  those  shown  in  Fig.  18,  the 
Wrights  warp  the  corners  of  the  planes  A  and 
A'.  Thus,  when  the  corners  i  and  2  are  ele- 
vated, the  corners  3  and  4  are  depressed.  This 
simultaneous  elevation  and  depression  of  cor- 
ners is  produced  by  a  cable  E,  attached  to  a 
lever  F'.  By  throwing  the  lever  from  side  to 


BALANCING   AEROPLANES       65 

side  the  planes  are  warped.  The  vertical  rud- 
der C  is  connected  by  tiller  ropes  with  the  same 
lever  F',  and  is  swung  by  moving  the  lever  P 
back  and  forth.  Hence  the  planes  are  warped 
and  the  vertical  rudder  properly  turned  by  the 
one  lever  F'.  The  photograph  reproduced  in 
Fig.  20  shows  Mr.  Wilbur  Wright  seated  in 
his  machine /with  his  hands  on  the  controlling 
levers.  Fig.  2 1  pictures  the  Wright  machine  on 
the  ground  and  shows  the  disposition  of  the  main 
planes,  horizontal  or  elevation  rudders,  and  ver- 
tical rudder.  Fig.  22  depicts  an  instruction 
machine  with  an  extra  lever  for  the  pupil. 

Some  of  the  machines  which  Mr.  Glenn  H. 
Curtiss  has  flown  are  similarly  provided  with 
two  superposed  main  planes  A  and  J9,  as 
shown  in  Fig.  23,  with  a  box-like  rudder  in 
front  and  with  a  rear  vertical  rudder  D.  The 
front  horizontal  rudder  is  swung  up  or  down 
by  means  of  the  rod  R  connected  with  the 
wheel  TV,  the  wheel  being  pushed  or  pulled  by 
the  pilot  for  that  purpose.  The  same  wheel  JV, 
when  rocked  like  the  pilot  wheel  of  a  steam- 
boat serves  to  swing  the  vertical  rudder  D  by 
drawing  on  one  or  the  other  of  two  tiller  ropes, 


66    THE    NEW   ART   OF    FLYING 

S.  In  his  earlier  machines,  as,  for  example, 
the  one  illustrated  in  Fig.  24,  Curtiss  employed 
supplementary  plane  tips,  very  much  like  those 
represented  in  Fig.  18.  In  his  later  machines, 
however,  one  of  which  is  shown  in  Fig.  25,  he 


FIG.  23.  — The  Curtiss  system  of  control. 

has  transferred  the  tips  from  the  sides  of  the 
main  planes  to  positions  between  the  main 
planes,  beyond  which  they  project,  as  indicated 
by  the  letters  C  C  in  Fig.  23.  Despite  the  trans- 
fer their  purpose  still  remains  the  same.  To 
swing  the  supplementary  planes  C  C  in  opposite 
directions,  cables  T  T  are  connected  with  the 
seat-back  G,  which  is  movable  from  side  to  side 


BALANCING   AEROPLANES       67 

and  which  partly  encircles  the  pilot's  body.  By 
throwing  his  body  from  side  to  side  the  pilot 
swings  the  planes  C  C  in  opposite  directions. 
The  effect  is  the  same  as  if  the  main  planes 
A  B  were  warped,  as  in  the  Wright  machine. 
Whether  or  not  it  is  necessary  to  throw  over 
the  vertical  rudder  when  the  balancing  planes 
C  C  are-  swung  is  the  question  at  issue  in 
the  patent  infringement  suit  instituted  by 
the  Wright  Brothers  against  Curtiss.  The 
Wrights  claim  that  Curtiss  cannot  fly  unless  the 
vertical  rudder  is  operated  simultaneously  with 
the  balancing  planes.  Curtiss  claims  that  he 
can.  Much  testimony  has  been  taken  on  both 
sides.  A  United  States  Circuit  Judge  thought 
that  the  preponderance  of  expert  evidence  was 
on  the  side  of  the  Wrights,  particularly  since 
Curtiss  himself  admitted  that  he  did  sometimes 
use  the  vertical  rudder  to  offset  the  swerving 
of  the  machine  caused  by  changing  the  incli- 
nation of  the  balancing  planes.  A  preliminary 
injunction  was  therefore  issued,  which,  on  ap- 
peal, however,  was  dissolved.  Whether  or  not 
Curtiss  can  fly  without  simultaneously  operat- 
ing his  vertical  rudder  and  his  balancing  planes 


68    THE   NEW   ART   OF   FLYING 


FIG.  26.  —  The  system  of  ailerons  and  rudders  devised 
by  Henry  Farman  for  maintaining  fore-and-aft  and 
side-to-side  balance. 


BALANCING   AEROPLANES       69 

will  be  decided  when  the  question  of  infringe- 
ment is  settled  at  the  final  hearing. 

In  the  Farman  biplane,  which  the  Wright 
Brothers  allege  likewise  infringes  their  patent, 
the  ailerons,  as  illustrated  in  Fig.  26,  form  part 
of  the  main  planes  A  B.  They  are  the  hinged 
flaps  D  D  at  the  rear  corners  of  the  main  planes. 
The  inclination  of  the  ailerons  D  D  is  varied  by 
means  of  cables  leading  to  the  lever  C.  By 
moving  the  lever  C  from  side  to  side,  the  aile- 
rons are  moved  up  and  down  in  opposite  direc- 
tions. To  the  rear  of  the  main  planes  two  ad- 
justable rudders  E  E  are  placed,  from  which  two 
wires  lead  to  a  tiller  F  operated  by  the  pilot's 
feet.  When  the  aeroplane  tips  to  the  left,  for 
example,  the  pilot  swings  his  control-lever  C  to 
the  right,  thus  pulling  down  on  the  flaps  on  the 
left-hand  side  of  the  planes  and  creating  more 
lift  on  that  side.  The  right-hand  flaps  remain 
horizontal,  held  out  by  the  air  pressure.  When 
the  machine  is  at  rest  on  the  ground,  the  flaps 
hang  down  vertically,  as  shown  in  Fig.  27.  In 
Fig.  28  Mr.  Farman  is  shown  seated  in  his 
biplane.  His  hand  grasps  the  lever  by  means 
of  which  both  the  ailerons  or  flaps  and  the 


70    THE    NEW   ART   OF    FLYING 

forward  horizontal  or  elevation  rudder  are 
operated. 

In  his  later  machines  Mr.  Curtiss  has  pro- 
vided ailerons  similar  to  those  of  Farman,  as 
shown  in  Fig.  29. 

The  Bleriot  monoplane,  which  is  also  in- 
volved in  this  Wright  litigation,  is  outwardly  at 


FIG.  30.  —  The  Bleriot  system  of  control. 

least  more  like  the  Wright  machine  in  the  mech- 
anism for  maintaining  side-to-side  balance.  Its 
single  supporting  plane  is  warped  at  the  sides 
by  a  lever  and  a  system  of  cables,  as  shown  in 
Fig.  30.  The  single  supporting  plane  is  rigidly 
trussed  along  its  front  edge,  but  a  cable  is  at- 
tached to  one  rear  corner  at  /  and  passes  down- 
ward, and  toward  the  centre  to  a  pulley  F 
(Fig.  31)  actuated  by  a  lever  K,  and  upward 


BALANCING   AEROPLANES       71 

to  the  opposite  rear  corner  of  the  plane  /' 
(Fig.  30).  By  moving  the  lever  K  to  one  side, 
the  cable  pulls  down  the  side  rear  portion  of  the 


FIG.  31.  —  The  steering  and  control  column  of  the  Bleriot 
monoplane.  The  wheel  L,  the  post  K,  and  the  bell-shaped 
member  M  form  one  piece  and  move  together.  Wires  O 
connect  the  bell  with  the  yoke  G,  carrying  the  pulley  F, 
around  which  the  wires  H  running  to  the  flexible  por- 
tions of  the  supporting  planes  are  wrapped.  By  rocking 
the  post  and  bell  from  side  to  side  in  a  vertical  plane 
the  wires  H  are  respectively  pulled  and  relaxed  to  warp 
the  planes.  By  moving  the  post  K  back  and  forth  the 
horizontal  rudder  is  operated  through  the  wires  P. 
These  various  movements  of  the  post  can  be  effected  by 
means  of  the  wheel  L,  which  is  clutched  by  the  aviator's 
hands,  or  by  means  of  the  bell  M,  which  can  be  clutched 
by  the  aviator's  feet  if  necessary. 


72    THE    NEW   ART    OF    FLYING 

plane  at  one  tip  to  a  greater  angle  of  incidence 
than  the  normal  plane  of  the  body  of  the  aero- 
plane, and  permits  the  opposite  side  rear  por- 
tion to  rise  to  an  angle  of  less  incidence.  Thus 
the  whole  plane  is  warped,  and  the  portions 
lying  at  the  opposite  tips  are  presented  to  the 
air  at  different  angles  of  incidence.  The  ver- 
tical adjustable  rudder  R  (Fig.  30)  is  located 
at  some  distance  to  the  rear  of  the  main  plane, 
and  wires  lead  from  it  to  a  tiller  operated  by 
the  feet.  When  the  pilot  warps  the  plane  he 
swings  the  rudder  to  prevent  the  machine  from 
spinning.  By  moving  the  lever  K  back  and 
forth  the  horizontal  rudder  is  rocked  up  and 
down. 

In  the  Antoinette  monoplane  the  horizontal 
or  elevation  rudder  and  the  stabilising  mech- 
anism are  quite  independent.  The  vertical 
rudder  consists  of  two  vertical  triangular  sur- 
faces at  the  rear.  They  are  moved  jointly  by 
means  of  wire  cables  running  from  a  tiller 
worked  by  the  aviator's  feet.  When  this  tiller, 
which  moves  in  a  horizontal  plane,  is  turned 
to  the  left,  the  aeroplane  will  turn  to  the  left. 
The  elevation  rudder  in  the  Antoinette  mon- 


II 

E    3 


bD 


BALANCING   AEROPLANES       73 

oplane  consists  of  a  single  triangular  horizon- 
tal surface  placed  at  the  extreme  rear.  It 
is  governed  by  cables  leading  from  a  wheel 
placed  at  the  aviator's  right  hand  (Fig.  32). 
To  ascend,  the  wheel  is  turned  up.  This 
causes  a  decrease  in  the  inclination  of  the  ele- 
vation rudder  relatively  to  the  line  of  flight,  and 
the  machine,  therefore,  rises.  Side-to-side  bal- 
ance was  at  one  time  maintained  by  ailerons,  as 
shown  in  Fig.  33.  Latterly  it  is  maintained  by 
warping  the  outer  ends  of  the  main  plane  very 
much  as  in  the  Wright  machine.  But  the  front 
ends  are  movable  and  the  rear  ends  rigid 
throughout  in  the  new  Antoinette,  while  the 
opposite  is  the  case  in  the  Wright  biplane.  The 
wheel  at  the  aviator's  left  hand,  through  cables 
and  a  sprocket  gear,  placed  at  the  lower  end  of 
the  central  mast,  controls  the  warping.  For  cor- 
recting a  dip  downward  on  the  right  the  right 
end  of  the  wing  is  turned  up,  and  at  the  same 
time  the  left  end  is  turned  down,  thus  restoring 
balance. 

Warping  a  plane  and  rocking  an  aileron  are 
not  the  only  ways  of  maintaining  side-to-side 
balance.  The  late  Professor  S.  P.  Langley  dis- 


74    THE    NEW   ART    OF    FLYING 

covered  that  by  cutting  a  plane  in  two  and  ar- 
ranging the  two  parts  so  that  they  would  form 
a  rather  wide  V  when  viewed  from  the  front 
or  rear  ("  dihedral  angle  "  is  the  proper  tech- 
nical term),  a  certain  amount  of  automatic  sta- 
bility would  be  obtained.  He  constructed  his 
own  successful  small  models  on  that  principle. 
Bleriot,  too,  adopted  it  in  at  least  one  of  his 
earlier  machines.  Although  wasteful  of  power 
it  is  still  a  conspicuous  feature  of  many  French 
machines  of  the  present  day.  Even  in  some 
recent  biplanes,  notably  the  racing  Farman,  it 
is  to  be  found. 

Still  another  way  of  obtaining  a  certain 
amount  of  automatic  stability  is  to  employ  ver- 
tical surfaces  to  prevent  tilting  and  to  distribute 
the  pressure  more  evenly  over  the  main  sur- 
faces. An  example  is  to  be  found  in  the  earlier 
Voisin  machine,  which  is  a  biplane  divided  into 
cells  by  vertical  curtains  or  partitions  (Fig. 
34).  In  practice,  these  partitions  are  found  in- 
adequate, for  which  reason  the  pilot  of  this 
Voisin  type  must  right  his  machine  by  steering 
with  the  rudder.  Thus,  if  the  machine  cants  up 
on  the  left  and  down  on  the  right,  he  steers  to 


BALANCING   AEROPLANES        75 

the  left.  This  brings  the  right  side  up  again 
because  it  is  suddenly  called  upon  to  travel  more 
quickly  through  the  air  than  the  left  side,  in- 
creased speed  resulting  in  increased  elevation. 
This  Voisin  type  is  one  of  the  few  construc- 
tions that  does  not  fall  within  the  scope  of  the 
Wright  patent.  Farman,  who  was  one  of  the 
first  pilots  that  ever  tried  a  Voisin,  abandoned 
it  for  the  aileron  machine,  which  bears  his  name. 
In  the  new  Voisin  machines  (Fig.  35)  no  cells 
at  all  are  to  be  found,  but  instead  ailerons  sim- 
ilar to  those  adopted  by  Farman.  On  the  whole 
it  must  be  confessed  that  the  most  successful 
machines  at  the  present  time  are  those  in  which 
the  side-to-side  balance  is  maintained  either  by 
warping  the  wings  or  by  means  of  ailerons. 

Sometimes  the  vertical  surfaces  are  distrib- 
uted along  the  frame  of  the  machine  in  the 
form  of  keels.  Although  they  contribute  a  cer- 
tain stability,  it  cannot  be  denied  that  they  also 
increase  the  resistance  and  lower  the  speed. 
To  prevent  this  so  far  as  possible,  and  yet  to 
retain  whatever  advantages  they  may  have,  it 
is  customary  to  taper  them.  Examples  of  such 
tapering  keels  will  be  found  on  the  Antoinette 


76    THE    NEW   ART   OF    FLYING 

and  Hanriot  monoplanes  (Fig.  36,  Frontis- 
piece). In  a  few  years  keels  will  probably  dis- 
appear altogether.  The  advantages  hardly 
offset  the  disadvantages.  No  special  arrange- 
ment or  design  of  keels  has  really  ever  suc- 
ceeded in  insuring  automatic  stability.  Even 
now  the  best  designers  confine  them  to  the 
extreme  rear  of  the  machine,  where  they  act 
somewhat  like  a  bird's  tail. 

Mr.  F.  W.  Lanchester,  the  distinguished 
English  authority,  has  suggested  that  auto- 
matic stability  can  be  insured  by  driving  the 
aeroplane  at  speeds  higher  than  those  of  the 
gusts,  that  are  so  liable  to  upset  it.  Just  as 
the  "  Lusitania  "  at  twenty-five  knots  dashes 
through  waves  and  winds  that  would  drive  a 
fishing-smack  to  cover,  so  the  high-speed  aero- 
plane, in  his  opinion,  would  sail  on,  undeterred 
by  the  fiercest  blast.  Sixty  miles  an  hour  is 
the  minimum  speed  that  a  machine  should  have, 
if  his  idea  is  correct.  Moreover,  he  believes 
that,  if  the  aeroplane  is  to  have  any  extended 
use,  it  must  travel  very  much  faster  than  the 
motor-car. 

Another  means  of  attaining  automatic  sta- 


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BALANCING   AEROPLANES        77 

bility  consists  in  varying  the  angle  of  incidence 
by  rocking  the  whole  plane  on  a  horizontal 
axis,  which  is  done  by  Esnault-Pelterie. 

The  foregoing  explanation  of  stability  and 
stabilizing  devices  applies  only  to  side-to-side 
balance.  Fore-and-aft  balance  can  be  obtained, 
as  in  birds,  by  tails,  such  as  are  found  in  the 
Curtiss,  Bleriot,  Antoinette,  Santos-Dumont, 
Esnault-Pelterie,  and  indeed  most  machines. 

The  tail  may  be  either  a  single  horizontal 
surface  or  a  cell,  like  a  box  kite.  'Almost  every 
machine  that  now  flies  is  provided  with  a  tail 
to  secure  steadiness  in  flight.  In  the  new 
Wright  biplanes  (Fig.  38)  a  single  horizontal 
surface  is  used  at  the  rear  of  the  machine,  a 
surface  which  also  serves  as  an  elevation 
rudder;  for  the  Wrights  have  removed  from 
the  front  of  the  machine  those  two  parallel 
horizontal  surfaces,  which,  in  the  early  days 
of  their  work,  were  to  them  like  the  antennae 
of  an  insect,  a  means  of  feeling  their  way.  The 
Wrights  were  the  first  who  ever  placed  the 
rudder  in  front,  and  their  example  was  quickly 
followed  by  Curtiss,  Farman,  Sommer,  Voisin 
and  other  biplane  makers.  Whatever  advan- 


78    THE    NEW   ART    OF    FLYING 

tages  this  forward  position  of  the  horizontal 
rudder  may  have,  it  is  certain  that  it  increases 
the  tendency  of  the  machine  to  pitch  in  flight, 
because  of  the  long  lever-arm  provided  by  the 
rods  connecting  the  forward  rudders  with  the 
main  framework.  When  the  Wrights  reversed 
themselves  and  removed  the  horizontal  rudder 
from  the  front  and  placed  it  at  the  rear,  where 
it  performed  not  only  its  old  function,  but  also 
served  as  a  tail  (an  instrument  with  which  the 
earlier  Wright  machines  were  not  provided), 
their  example  was  promptly  followed  by 
Voisin  (Fig.  35),  Breguet,  Goupy,  Caudron 
Freres  and  other  constructors.  It  is  safe  to 
predict  that  in  the  future  most  biplanes  will  be 
provided  with  rear  horizontal  stabilising  and 
elevating  surfaces. 

From  the  very  first,  monoplanes  have  been 
provided  with  rear  horizontal  or  elevation 
rudders,  probably  because  such  is  the  example 
offered  by  every  bird  and  because  the  late  Pro- 
fessor Langley  adopted  them  after  much  ex- 
perimenting. The  Bleriot,  Antoinette  and 
other  monoplanes  have  rear  horizontal  rudders 
and  also  tails. 


BALANCING   AEROPLANES        79 

The  tail  corrects  the  see-saw  motion  or  pitch- 
ing of  a  flying-machine  in  flight.  The  further 
back  that  it  is  placed  the  greater  will  be  the 
steadying  effect.  If  placed  too  far  back,  how- 
ever, a  "  dead  centre  "  will  be  reached.  If 
there  is  no  tail  the  pilot  must  manipulate  the 
horizontal  rudder  to  check  the  see-saw  motion. 
The  Wrights  have  taken  out  a  patent  for  a 
mechanical  device,  which  maintains  fore-and- 
aft  stability  automatically.  In  this  device  the 
human  brain  is  supplanted  by  the  pressure  of 
the  air  on  a  plane.  Compressed  air  is  substi- 
tuted for  muscular  action.  Lateral  stability  is 

automatically  maintained  by  means  of  a  pendu- 

• 

lum.  The  plane  and  pendulum  open  valves 
which  admit  compressed  air  to  an  engine  oper- 
ating the  horizontal  or  elevation  rudder  and 
warping  mechanism. 

To  relieve  the  pilot  of  the  physical  strain  of 
more  or  less  constantly  warping  planes  or  ma- 
nipulating ailerons,  it  was  suggested  long  be- 
fore the  day  of  the  Wrights  that  the  flying- 
machine  be  provided  with  some  automatic 
device  which  would  prevent  any  capsizing 
tendency.  The  more  important  of  such  ap- 


8o    THE    NEW   ART    OF    FLYING 

pliances  are  moving  weights,  pendulums,  and 
gyrostats.  A  gyrostat  is  any  rapidly  rotating 
body,  which,  by  virtue  of  its  rotation,  resists 
any  force  tending  to  move  it  from  its  plane  of 
rotation.  The  greater  the  weight  and  the 
higher  the  speed  of  the  gyrostat  the  greater 
must  be  the  force  expended  to  shift  it  from  its 
plane  of  rotation.  Hence  if  a  gyrostat  could 
be  mounted  on  an  aeroplane  it  certainly  would 
tend  to  resist  any  unbalancing  force,  such  as  a 
gust  of  wind.  Paul  Regnard  in  France  is  said 
to  have  conducted  very  successful  experiments 
with  gyrostatically  controlled  aeroplanes.  Rob- 
erts in  England  has  also  made  more  or  less  en- 
couraging tests.  In  his  machine  the  gyrostat 
is  applied  as  shown  in  Fig.  37. 

The  pilots  of  present  machines  object  to  any 
device  that  will  relieve  them  entirely  of  all  hand 
control.  They  would  much  prefer  an  auto- 
matic device  which  is  immediately  thrown  out 
of  operation  when  the  hand-devices  are  manipu- 
lated. It  is  argued  that  a  machine  must  be 
humoured,  that  with  an  automatic  device  such 
as  the  gyrostat,  it  is  impossible  to  accommo- 
date the  machine  to  variations  in  the  wind. 


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BALANCING   AEROPLANES        81 

Moreover,  there  is  the  objection  that  the  ma- 
chine must  be  elevated  rapidly  in  starting,  with 
a  fairly  large  angle  of  incidence,  but  must  after- 
wards assume  a  fairly  flat  angle  for  horizontal 
flight,  with  all  of  which  a  steadily  running  gyro- 
stat would  seriously  interfere.  Soaring  down 
a  steep  angle  with  motors  at  full  speed  could 
hardly  be  accomplished  with  a  gyrostat  run- 
ning at  a  fixed  rate,  for  it  is  the  gyrostat's 
tendency  to  resist  movement.  Besides,  there 
is  always  the  possibility  that  the  motor  which 
drives  the  gyrostat  may  stop,  so  that  the  avi- 
ator is  helpless  if  no  hand-controlled  devices 
enable  him  to  prevent  rocking  from  side  to  side 
and  pitching  fore  and  aft. 

The  pendulum,  as  we  have  seen,  has  been 
suggested  by  the  Wrights  as  well  as  by  other 
inventors  to  relieve  the  aviator  of  his  present 
duties.  The  underlying  idea  is  that  a  freely 
suspended  weight  will  always  tend  to  hang 
down,  and  that  it  would  be  an  easy  mat- 
ter to  connect  with  it  elevation  rudders  and 
ailerons,  in  such  a  manner  that  pitching  fore 
and  aft,  or  rocking  from  side  to  side  could  be 
controlled  by  the  effort  of  the  pendulum  to 


82  THE  NEW  ART  OF  FLYING 
assume  a  perfectly  normal  position  relatively 
to  the  earth.  The  pendulum,  however,  will 
hardly  be  likely  to  attain  the  desired  end.  It 
cannot  control  a  flying-machine  automatically, 
as  Professor  Prandtl  has  pointed  out.  The 
very  force  which  causes  an  aeroplane  to  change 
its  horizontal  position  in  flight  also  retards  it, 
accelerates  it,  or  inclines  it  from  side  to  side. 
Consequently  a  pendulum,  which  has  the  mo- 
mentum of  the  entire  machine,  will  follow  the 
direction  of  the  aeroplane's  inclination  and, 
so  far  from  hanging  down,  will  deviate  from 
the  vertical.  The  result  will  be,  curiously 
enough,  that  it  will  always  maintain  its  posi- 
tion relatively  to  the  planes,  whatever  their 
inclination  fore-and-aft  and  side-to-side  may  be. 
Hence  the  pendulum  is  inoperative.  Further- 
more, when  an  aeroplane  is  rounding  a  curve 
at  the  rate  of  from  forty  to  sixty  miles  an  hour, 
centrifugal  force  would  completely  nullify  the 
action  of  the  pendulum. 

If  a  gyrostat  is  to  be  used,  it  is  likely  that 
it  will  be  combined  with  some  system  of  hand 
control,  so  that  the  aviator  can  depend  upon  the 
one  or  the  other,  as  circumstances  may  dictate. 


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BALANCING   AEROPLANES        83 

But  how  this  combination  would  really  im- 
prove the  situation  it  is  difficult  to  see.  .Auto- 
matic control  is  necessarily  complicated.  Hand 
control  is  admittedly  dependent  upon  a  cool 
head  and  an  expert  hand.  Moreover,  an  auto- 
matic device  must  be  made  as  small  and  as  light 
as  possible,  for  the  aeroplane  as  it  now  stands  is 
a  machine  in  which  the  weight  of  every  part 
has  been  reduced  to  a  minimum.  Can  control 
mechanism,  dependent  upon  a  gyrostat,  be 
made  sufficiently  light  to  meet  the  requirements 
of  present  construction?  The  more  one  con- 
siders the  question,  the  more  likely  are  we  to 
believe  that  the  best  automatic  machine  is  a 
well-trained  hand. 

Any  one  who  has  seen  a  skilled  man  steering 
a  small  boat  in  a  heavy  sea  must  realise  that 
there  is  no  possibility  of  making  any  automatic 
device  which  would  take  his  place,  and  that 
any  attempt  to  make  the  steering  automatic 
by  such  means  as  a  gyrostat  would  mean  the 
certain  swamping  of  the  boat  in  a  sea  through 
which  it  could  be  steered  quite  simply  by  hand. 
The  aeroplane  is  very  much  in  the  position  of 
this  small  boat. 


84    THE    NEW   ART    OF    FLYING 

The  danger  of  hand  control  is  to  be  found 
in  the  possibility  of  making  a  false  move. 
Locomotive  engineers,  signal  men,  automobile 
chauffeurs,  are  all  of  them  in  a  position  where 
a  false  move  means  a  bad  accident.  Yet  for 
all  that,  the  number  of  errors  which  are  made 
is  comparatively  small.  A  ship  is  dependent 
upon  the  engines  and  skill  of  the  men  in  the 
pilot  house ;  yet  it  is  but  rarely  that  we  hear 
of  shipwrecks  due  to  bad  judgment  in  the 
wheel  house.  All  things  considered,  it  is  very 
likely  that  aeroplanes  will  be  hand  controlled 
for  years  to  come. 


CHAPTER   VI 

MAKING  A   TURN 

IN  straightaway  flight  an  aeroplane  is  balanced 
to  a  certain  extent  by  the  main  supporting  sur- 
faces (the  large  spread  of  which  counteracts 
sudden  inclination)  and  also  by  the  position  of 
the  centre  of  gravity,  which  lies  below  the  sup- 
porting surfaces  in  many  machines.  But  when 
the  vertical  rudder  is  thrown  over  to  swing  the 
machine  around,  new  forces  come  into  play. 

When  a  line  of  soldiers  wheels  around  a 
street  corner  the  man  at  the  inner  end  of  the 
line  does  little  more  than  mark  time;  the  man 
in  the  centre  of  the  line  marches  along  at  a 
steady  pace;  while  the  man  on  the  outside  all 
but  runs.  In  order  that  the  line  may  be  straight 
the  movement  must  be  progressively  faster 
from  the  inner  to  the  outer  end.  An  aeroplane 
as  it  turns  horizontally  is  in  exactly  the  same 
predicament  as  a  line  of  soldiers.  The  outer 
end  of  the  machine  must  move  faster  than  the 
inner  end. 


86    THE    NEW   ART   OF    FLYING 

The  accompanying  illustration,  Fig.  39,  will 
make  this  clearer.  Let  us  assume  that  the  arc 
to  be  described  is  sixty  feet  in  diameter,  and 


\ 


FIG.  39.  —  An  aeroplane  of  40  feet  spread  of  wing  round- 
ing an  arc  of  60  feet  radius.  Since  the  outer  side  of  the 
aeroplane  must  travel  over  a  given  distance  in  the  same 
time  that  the  inner  side  must  travel  a  considerably 
shorter  distance,  gravitation  must  be  opposed  to  centrif- 
ugal force  in  order  that  the  turn  may  be  effected  with 
safety. 


that  the  aeroplane  has  a  spread  of  forty  feet. 
The  outer  end  of  the  machine  must  describe  its 
large  arc  of  sixty  feet  radius  while  the  inner 
end  is  describing  its  small  arc  of  twenty  feet 


MAKING   A   TURN  87 

radius.  Evidently  the  outer  end  must  travel 
considerably  faster  than  the  inner. 

As  the  speed  of  an  aeroplane  increases,  its 
lifting  power  also  increases.  Hence  the  more 
rapidly  moving  outer  end  of  an  aeroplane  will 
be  subjected  to  a  greater  lifting  effort  than  the 
slowly  moving  inner  end,  and  hence  the  entire 
machine  is  canted  at  a  more  or  less  sharp  angle 
on  a  turn.  This  natural  canting  or  banking  has 
its  advantages.  It  counteracts  the  effects  of 
centrifugal  force,  which  are  unavoidable  in  any 
rotary  movement. 

What  centrifugal  force  means  we  see  when 
a  weight  at  the  end  of  a  cord  is  whirled  around. 
If  whirled  fast  enough,  the  weight  will  describe 
a  circle,  because  the  centrifugal  force  is  very 
much  greater  than  the  force  of  gravitation.  If 
the  whirling  be  slackened  below  a  certain  criti- 
cal point,  the  weight  will  drop  back  to  the 
hand.  A  flying-machine  is  like  the  whirling 
stone.  It  has  a  very  large  centrifugal  force 
as  it  turns.  So  great  is  that  force  that  it  must 
be  checked  by  the  force  of  gravitation,  in  other 
words,  the  weight  of  the  machine.  The  more 
the  machine  is  heeled  over,  the  more  marked 


88    THE    NEW   ART   OF    FLYING 

will  be  the  action  of  gravitation.  Hence  the 
natural  canting  of  the  machine  on  a  curve  is  of 
advantage  in  counteracting  the  effect  of  centrif- 
ugal force. 

If  the  canting  be  very  pronounced,  it  is  pos- 
sible that  gravitation  may  overcome  the  centrif- 
ugal force,  so  that  the  machine  will  slide  down 
to  the  ground.  To  forestall  that  possibility  the 
aviator  may  either  sweep  his  circle  on  so  long 
a  radius  that  there  will  be  but  little  canting,  or 
he  may  employ  wing-warping  devices  or  aile- 
rons to  counterbalance  the  canting  action.  Since 
most  aeroplanes  are  provided  with  either  warp- 
ing devices  or  ailerons,  it  is  the  usual  practice 
to  depend  upon  them  in  turning.  The  result  is 
that  we  see  skilful  pilots  swinging  in  an  arc  at 
a  speed  that  cants  their  machines  at  an  angle 
which  may  be  more  than  seventy  degrees  to  the 
horizontal  and  which  almost  causes  the  specta- 
tor's heart  to  stop  beating,  so  perilous  does  the 
exploit  seem  to  the  eye. 

The  inquiring  reader  may  ask:  How  does 
wing-warping  or  the  manipulation  of  ailerons 
prevent  the  machine  from  slipping  down  ?  The 
principle  involved  is  exactly  the  same  as  that 


A 


Photograph  by  Edwin  Levick 

Fig.  28. — Henry  Farman  seated  in  his  biplane.     His 

hand  grasps  the  lever  by  which  the 

ailerons  are  operated 


MAKING   A   TURN  89 

which  underlies  the  balancing  of  the  machine 
in  straightaway  flight  when  it  is  subjected  to  cap- 
sizing gusts.  As  soon  as  the  pilot  wheels,  he  in- 
creases the  angle  of  incidence  on  the  inner  end 
and  hence  the  upward  pressure,  with  the  result 
that  the  tendency  of  the  inner  end  of  the  ma- 
chine to  fall  is  checked.  Simultaneously  the 
angle  of  incidence  of  the  outer  side  is  decreased 
and  the  downward  pressure  increased,  with  the 
result  that  the  .tendency  of  the  outer  side  to  rise 
is  checked. 

All  this  sounds  very  easy;  yet,  even  after  a 
successful  aeroplane  had  been  invented,  many 
machines  were  wrecked  before  the  trick  of 
making  a  turn  was  learned.  It  took  the  French 
two  years  to  learn  the  art  of  turning.  Indeed, 
a  wealthy  Parisian,  named  Armengaud,  offered 
a  prize  to  the  first  Frenchman  who  performed 
the  feat.  Henry  Farman  won  that  prize  so 
recently  as  July  6,  1908.  The  Wright  Brothers 
spent  the  whole  flying  season  of  1904  in 
learning  how  to  sweep  a  circle  when  the  wind 
was  blowing.  Octave  Chanute,  the  only  en- 
gineer who  was  allowed  to  see  them  at  work 
during  that  period  of  apprenticeship,  gives 


9o    THE    NEW   ART   OF    FLYING 
this    interesting    account    of    their    trials    and 
tribulations : 

"  I  witnessed  a  flight  at  Dayton  on  October 
15,  1904,  of  1,377  feet>  performed  in  twenty- 
four  seconds.  The  start  was  made  from  level 
ground,  and  the  machine  swept  over  about  one- 
quarter  of  a  circle  at  a  speed  of  thirty-nine 
miles  an  hour.  The  wind  was  blowing  diag- 
onally to  the  starting  rail  at  about  sixteen  miles 
an  hour. 

"  After  the  machine  had  progressed  some 
five  hundred  feet  and  then  risen  about  fifteen 
feet  it  began  to  cant  over  to  the  left  and  as- 
sumed an  oblique  transverse  inclination  of  fif- 
teen to  twenty  degrees.  Had  this  occurred  at 
an  elevation  of,  say,  one  hundred  feet  above 
the  ground,  Orville  Wright,  who  was  in  the 
machine  on  this  occasion,  could  have  recovered 
an  even  balance  even  with  the  rather  imperfect 
arrangement  for  control  at  that  time  employed. 
But  he  felt  himself  unable  to  do  so  at  the  height 
then  occupied  and  concluded  to  come  down. 

*  This  was  done  while  still  turning  to  the 
left,  so  that  the  machine  was  going  with  the 
wind  instead  of  against  it,  as  practiced  where 
possible. 

"  The  landing  was  made  at  a  speed  of  forty- 
five  to  fifty  miles  an  hour,  one  wing  striking  the 


MAKING   A   TURN  91 

ground  in  advance  of  the  other,  and  a  breakage 
occurred,  which  required  one  week  for  repairs. 
The  operator  was  in  no  wise  hurt. 

"  This  was  flight  No.  71  of  the  1904  series. 
On  the  preceding  day  the  brothers  had  made 
alternately  three  circular  flights,  one  of  4,001 
feet,  one  of  4,902  feet,  and  one  of  4,936  feet, 
the  last  covering  rather  more  than  a  full  circle.11 

A  steady  wind  is  imperceptible  to  the  man  in 
a  flying-machine,  and  turning  is  effected  as 
easily  with  as  against  the  wind.  When  the 
wind  is  unsteady  not  only  is  balancing  difficult 
but  turning  also,  since  the  machine  must  be 
simultaneously  balanced  and  turned.  The  two 
operations  are  more  or  less  confused.  When 
the  wind  is  very  gusty  the  pilot  may  find  it 
harder  to  turn  and  travel  with  the  wind  instead 
of  against  it. 

A  sharp  turn  on  an  aeroplane  is  like  one  of 
those  moments  on  a  yacht  when  you  slack  away 
quickly  on  the  main  sheet  and  prepare  for  the 
boom  to  jibe.  There  is  none  of  the  yacht's 
hesitancy,  however;  for  the  machine  slides 
away  on  the  new  slant  without  a  quiver.  An 
inexperienced  passenger  on  an  aeroplane  is 


92     THE    NEW   ART    OF    FLYING 

tempted  to  right  the  machine,  as  it  swings 
around  and  tilts  its  wings,  by  throwing  over  his 
body  toward  the  descending  side.  In  a  canoe 
or  on  a  bicycle  it  would  be  natural  to  use  the 
body.  In  an  aeroplane  the  movement  is  un- 
necessary because  the  machine  does  its  own 
banking. 

In  the  Curtiss  and  Santos-Dumont  machines 
any  such  instinctive  movement  on  the  part  of 
the  aviator  to  right  the  careening  machine  actu- 
ates the  ailerons  or  wing-warping  devices  in 
the  proper  way.  In  the  Curtiss  biplane,  as  we 
have  seen,  the  seat-back  is  pivoted  and  is  con- 
nected by  cables  with  the  ailerons.  Hence, 
should  the  pilot  involuntarily  throw  his  weight 
over  to  right  the  machine,  the  ailerons  are 
tilted  to  regulate  the  pressure  on  the  planes  in 
the  proper  manner. 

The  effect  of  the  vertical  rudder  in  turning 
varies  with  the  speed  of  the  aeroplane  relatively 
to  the  speed  of  the  wind.  The  higher  the 
speed  of  the  aeroplane  the  more  marked  is  the 
influence  of  the  vertical  rudder  on  its  course. 

The  form  that  the  vertical  rudder  assumes 
is  various.  In  monoplanes  it  consists  of  a 


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MAKING   A   TURN  93 

single  vertical  surface,  mounted  at  the  rear  of, 
the  machine:  in  biplanes  it  usually  consists  of 
a  pair  of  parallel  vertical  surfaces,  as  in  the 
Wright  machine.  Occasionally  these  parallel 
vertical  surfaces  form  the  sides  of  a  box,  as 
in  the  Voisin  and  Farman  machines,  the  top 
and  bottom  of  the  box  serving  as  horizontal 
stabilising  surfaces,  as  in  the  old  cellular  Voisin 
biplane. 


CHAPTER    VII 

THE    PROPELLER 

FEATHERING  paddles,  somewhat  like  those  to 
be  found  on  steamboats,  beating  wings,  like 
those  of  a  bird,  sweeps  or  oars  have  all  been 
suggested  as  means  for  propelling  the  flying- 
machine;  but  the  screw  propeller  is  the  only 
device  that  has  met  with  any  success.  The  screw 
propeller  is  the  most  important  adjunct  of  the 
aeroplane,  and  also  the  most  deficient.  The 
circumstance  is  remarkable  because  the  screw 
or  helical  rotating  propeller  was  associated 
with  schemes  of  aerial  navigation  no  less  than 
four  centuries  ago,  and  by  no  less  a  personage 
than  the  great  artist-mechanician,  Leonardo  da 
Vinci,  at  the  end  of  the  fifteenth  century. 

Leonardo  da  Vinci's  propeller  was  a  screw 
or  helix  of  a  single  "  worm  "  or  thread  —  prac- 
tically all  "  worm  "  —  comprising  an  entire 
convolution,  of  which  the  modern  equivalent 
would  be  a  single-bladed  screw,  blades  being 
a  much  later  development.  It  is  not  difficult 


THE    PROPELLER  95 

to  imagine  how  the  original  screw  propeller 
came  to  be  of  the  single  "  worm  "  type,  and 
why  one  complete  turn  of  the  "  worm  "  should 
be  deemed  essential.  These  were  matters  of 
subsequent  development,  the  departures  being 
suggested  by  experiment  and  trial. 

It  was  first  discovered  by  actual  comparative 
trials  that  half  a  convolution  of  the  "  worm  " 
was  fully  as  efficient  as  a  whole  turn,  and  then 
that  a  quarter  turn  was  more  efficient  than  half. 
But  with  this  curtailment  of  the  helix  a  for- 
midable difficulty  arose.  It  had  now  developed 
Into  a  one-bladed  screw;  it  was  unsymmetrical 
and,  consequently,  unbalanced.  Centrifugal 
force  and  one-sided  thrust  jointly  interposed, 
with  poor  results. 

Eventually  it  dawned  on  the  minds  of  the 
pioneer  experimenters  that  to  produce  a  more 
efficient,  symmetrical,  and  compact  screw  pro- 
peller—  while  employing  only  a  fraction  of 
a  convolution  —  two  or  more  "  worms,"  now 
reduced  to  blades,  were  necessary. 

No  perfect  definition  of  a  screw  propeller 
has  ever  been  given.  It  is  usually  defined  as 
an  organ  which,  by  pressing  upon  a  fluid,  pro- 


96     THE    NEW   ART   OF    FLYING 

pels  the  vehicle  to  which  it  is  attached.  In  a 
sense,  the  screw  propeller  may  be  regarded  as 
a  rotating  aeroplane,  with  an  angle  of  inci- 
dence, known  as  its  "  pitch,"  and  a  "  camber," 
which  is  its  curve.  But  the  propeller  differs 
from  the  aeroplane  in  that  the  blades  are  con- 
tinually passing  over  the  same  spot  many  times 
in  a  second  in  air  already  disturbed.  This  is 
one  reason  why  the  propeller  offers  a  far  more 
difficult  problem  than  the  plane. 

By  the  "  pitch  "  of  a  propeller  is  meant  the 
theoretical  distance  that  the  propeller  would 
move  forward  in  one  revolution  in  a  solid. 
Because  a  propeller  revolves  in  air,  a  very 
thin  and  yielding  medium,  it  loses  a  certain 
amount  of  power,  which  loss  is  known  as  its 
"  slip."  If  the  propeller  in  one  revolution 
moves  forward  theoretically  six  inches,  but  actu- 
ally only  three  inches,  the  loss  of  power  or 
"  slip  "  is  fifty  per  cent.  The  slip  varies  with 
different  speeds.  To  find  the  best  pitch,  the  best 
curvature,  the  best  diameter,  the  best  speed,  is 
the  problem  that  confronts  the  propeller  designer. 

The  ideal  aerial  propeller  is  one  that  can 
move  through  the  air  without  friction.  If  the 


THE    PROPELLER  97 

ideal  could  be  attained,  the  entire  power  of  the 
motor  would  be  transformed  into  useful  work, 
and  a  maximum  thrust  would  be  transmitted  to 
the  propeller  shaft.  The  actual  aerial  propeller 


FIG.  41.  —  A  single-threaded  and  a  double- threaded  screw. 
A  two-bladed  aeroplane  propeller  may  be  conceived  to 
have  been  cut  from  a  double-threaded  screw,  i.  e.,  the 
sections  A  and  A'  and  the  sections  B  and  Br. 

falls  far  short  of  that  ideal.  Its  blades  are  not 
plane,  but  are  curved  in  a  manner  skilfully  de- 
signed to  obtain  a  maximum  efficiency.  In  order 
to  give  an  idea  of  this  curvature  and  its  pos- 
sible variations,  consider  a  vertical  section  of 
an  Archimedes  screw  (Fig.  41),  Let  us  study 


98     THE    NEW   ART   OF    FLYING 

the  small  slice,  M.  This  small  element  is  not 
a  plane  surface,  but  has  a  curvature  which  de- 
pends upon  the  pitch  of  the  screw  and  its  radius. 
Two  such  elements  attached,  opposite  each 
other,  to  the  same  shaft  represent  a  two-bladed 
propeller  of  definite  curvature. 

It  is  evident  that  this  curvature  cannot  be  a 
matter  of  indifference,  for  it  is  intimately  con- 
nected with  the  distance  A  5,  between  two 
points  on  the  same  generatrix  of  the  screw; 
that  is  to  say,  upon  the  pitch  of  the  screw.  The 
form  of  a  propeller  blade  can  be  imitated  by 
holding  one  end  of  a  rectangular  strip  of  paper 
and  twisting  the  other  end  about  an  axis  parallel 
with  the  length  of  the  strip.  The  Wrights  form 
such  a  surface  in  deforming  aeroplanes  in  steer- 
ing. If  the  aeroplane  were  attached  to  a  fixed 
vertical  axis,  it  would  revolve  about  this  axis 
like  an  ordinary  propeller  during  a  turn.  The 
true  screw-propeller  in  its  simplest  and  most 
efficient  type  is  but  a  very  short  length  cut  from 
a  two-thread  screw,  in  which  the  thread  is  rela- 
tively very  deep,  with  a  pitch  equal  to  about 
two  thirds  of  its  diameter.  A  twist  or  curve  in 
a  propeller  blade  is  necessary  because  the  hub 


THE    PROPELLER  99 

and  the  outer  edge  of  the  blade  revolve  at 
different  speeds.  The  outer  edge  of  the  blade 
clearly  must  sweep  through  a  greater  distance 
in  a  given  time  than  the  hub.  In  order  that  all 
parts  may  theoretically  grip  the  air  equally,  the 
angle  is  steeper  at  the  centre  than  at  the  outer 
edge.  In  practice  the  hub  portion  has  a  much 
lower  efficiency  than  the  outer  edge  of  the 
blade. 

Just  how  many  blades  the  propeller  should 
have  once  gave  us  much  concern.  Some  air- 
propellers  have  two  blades,  some  three,  some 
four.  It  is  now  generally  conceded  that  nothing 
is  to  be  gained  by  three  and  four  blades,  and 
that  the  two-bladed  propeller  is  indeed  the  most 
efficient. 

The  Ericsson  propeller  (marine)  was 
formed  of  a  short  section  of  a  12-thread  screw 
of  very  coarse  pitch  and  proved  very  ineffi- 
cient. The  aerial  fan  propeller  of  Moy  (not 
a  screw)  had  six  broad  vanes  enclosed  in  a 
hoop  and  was  but  little  better.  The  same  re- 
mark applies  to  the  propellers  of  Henson, 
Stringfellow,  Linfield,  Du  Temple,  and  many 
others.  Even  the  first  propeller  fans  used  by 


ioo    THE    NEW   ART   OF    FLYING 

Langley  on  his  earliest  aerial  model  were  six- 
bladed.  In  his  subsequent  and  highly  success- 
ful model  aerodrome  the  twin  propellers  were 
two-bladed  true  screws,  as  also  were  those  of 
the  Maxim  machine. 

It  is  a  significant  fact  that  the  conspicuous 
successes  have  all  been  achieved  with  two- 
bladed  propellers.  All  recent  systematic  and 
comparative  experiment  points  to  the  fact  that 
a  two-bladed  propeller  is  the  most  efficient,  and, 
at  the  same  time,  fortunately,  the  simplest  and 
lightest. 

Authorities  are  not  in  accord  on  the  proper 
position  of  the  propeller.  Most  of  them,  how- 
ever, hold,  with  Sir  Hiram  Maxim,  that  the 
proper  position  is  in  the  rear.  Bleriot  (Fig. 
46),  Levavasseur  (who  builds  the  Antoinette 
machine),  and  many  monoplane  designers 
mount  the  propeller  in  front.  In  its  usual  posi- 
tion just  in  advance  of  the  centre,  the  front  pro- 
peller interrupts  the  entering  edge.  To  obviate 
this,  some  monoplane  builders,  among  them 
Santos-Dumont  and  Bleriot  (in  his  passenger- 
carrying  monoplane  XII),  place  the  engine  and 
pilot  below  the  plane. 


THE    PROPELLER  101 

On   the   position   of   the   propeller    Maxim 
says: 

"  Many  experimenters  have  imagined  that  a 
screw  is  just  as  efficient  placed  in  front  of  a 
machine  as  at  the  rear,  and  it  is  quite  probable 
that  in  the  early  days  of  the  steamship  a  similar 
state  of  things  existed.    For  several  years  there 
were  steamboats  running  on  the  Hudson  River, 
New  York,  with  screws  at  their  bows  instead 
of  at  their  stern.     Inventors  of,  and  experi- 
menters  with,    flying-machines   are   not   at   all 
agreed  by  any  means  as  to  the  best  position  for 
the  screw.    It  would  appear  that  many,  having 
noticed  that  a  horse-propelled  carriage  always 
has  the  horse  attached  to  the  front,  and  that 
their  carriage  is  drawn  instead  of  pushed,  have 
come  to  the  conclusion  that  in  a  flying-machine 
the  screw  ought,  in  the  very  nature  of  things, 
to  be  attached  to  the  front  of  the  machine,  so 
as  to  draw  it  through  the  air.     Railway  trains 
have  their  propelling  power  in  front,  and  why 
should  it  not  be  the  same  with  flying-machines? 
But  this  is  very  bad  reasoning.     There  is  but 
one  place  for  the  screw,  and  that  is  in  the  imme- 
diate wake,  and  in  the  centre  of  the  greatest 
atmospheric  disturbance.  ...  If  the  screw  is 
in  front,  the  backwash  strikes  the  machine  and 
certainly  has  a  decidedly  retarding  action.    The 


102    THE    NEW   ART    OF    FLYING 

framework,  motor,  etc.,  offer  a  good  deal  of 
resistance  to  the  passage  of  the  air,  and  if  the 
air  has  already  had  imparted  to  it  a  backward 
motion,  the  resistance  is  greatly  increased." 

When  mounted  in  front,  the  screw  draws 
the  machine  along.  Hence  the  front  propeller 
is  sometimes  called  a  "  tractor  screw."  When 
the  screw  is  mounted  in  the  stern,  as  in  a  ship, 
it  pushes  the  machine  along  (Fig.  48)  and  is 
then  truly  a  propeller. 

The  question  of  position  is  not  yet  settled 
by  any  means.  The  propeller  at  the  rear  has  a 
free  discharge,  but,  on  the  other  hand,  its  feed 
is  disturbed.  In  front  it  has  a  clear  feed,  but 
is  hampered  in  discharging,  and  also  modifies 
the  streams  impinging  on  the  supporting  planes, 
as  Maxim  points  out. 

The  number  of  the  propellers  is  also  a  moot 
point.  Kress,  a  well-known  experimenter,  be- 
lieved that  there  should  be  at  least  four  pro- 
pellers, so  attached  that  their  shafts  could  be 
directed  to  different  angles.  Thus,  he  imag- 
ined, they  could  be  employed  to  sustain  the 
machine  in  the  air  without  driving  it  forward. 
This  is  the  helicopter  or  screw-flier  principle, 


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THE    PROPELLER  103 

briefly  considered  in  the  chapter  on  flying- 
machine  types. 

The  Wrights  have  always  advocated  the  use 
of  two  propellers  rotating  in  opposite  direc- 
tions (Fig.  44).  There  is  always  the  danger, 
however,  that  one  propeller  may  break  down 
and  that  the  machine  may  be  imperilled.  In- 
deed, an  accident  of  that  kind  occurred  during 
the  official  tests  of  the  Wright  machine  at 
Fort  Myer,  Virginia,  in  1908.  A  propeller 
struck  a  loose  guy-wire  and  broke.  The  biplane 
crashed  to  the  ground.  Orville  Wright,  the 
pilot,  was  painfully  injured,  and  Lieutenant 
Selfridge,  a  passenger,  was  killed.  It  must  be 
stated,  however,  that  had  the  machine  been 
higher,  Mr.  Wright  would  probably  have  glided 
down  in  safety. 

Should  propellers  be  of  very  small  diameter 
and  high  speed,  or  of  large  diameter  and  low 
speed?  Both  systems  have  their  advocates. 
We  know  something  about  the  power  of  heavy 
gales;  and  when  we  consider  that  an  aero- 
plane propeller  is  capable  of  producing  a 
little  cyclone,  it  is  easy  to  conceive  of  its 
exerting  sufficient  force  to  drive  a  i,ooo-pound 


io4    THE    NEW   ART   OF    FLYING 

aeroplane  at  high  velocity.  Flying-machines 
have  attained  a  speed  of  seventy  miles  an 
hour.  In  order  to  do  this,  the  propellers  must 
have  turned  fast  enough  to  have  produced  a 
current  of  air  considerably  more  than  this  veloc- 
ity, because  the  fluidity  and  elasticity  of  the  air 
are  sufficient  to  cause  a  considerable  "  slip  "  of 
the  propellers,  which  reduces  their  efficiency  to 
a  large  extent.  Hence  even  the  slowest  of  pro- 
pellers (the  Wright)  turns  at  the  fairly  high 
speed  of  four  hundred  revolutions  a  minute, 
while  the  swiftest  turns  at  the  rate  of  about 
fifteen  hundred  revolutions  a  minute,  which  is 
about  the  speed  of  an  electric  fan.  A  high- 
speed Chauviere  propeller  is  a  mere  glittering 
disk  of  light  about  eight  feet  in  diameter.  The 
blades  move  so  fast  that  it  is  possible  to  cast 
a  shadow  upon  them;  for  the  eye  cannot  per- 
ceive the  interval  which  elapses  before  another 
blade  has  taken  the  place  of  that  which  has  left 
a  given  spot.  The  phenomenon. is  simply  one 
of  the  persistence  of  retinal  images ;  but  it  serves 
to  drive  home  the  enormous  speed  of  some 
aeroplane  propellers. 

It  is  generally  believed  that  much  better  re- 


THE    PROPELLER  105 

suits  could  be  obtained  by  the  use  of  propellers 
of  fifteen  or  twenty  feet  diameter  rotating 
slowly.  But  there  are  two  disadvantages  in- 
volved in  this  feature  of  construction,  which 
make  its  adoption  in  the  machines  of  the  future 
rather  doubtful.  The  first  is  the  greatly  added 
weight  of  so  big  a  propeller;  and  the  second, 
the  difficulty  of  building  a  good  chassis  high 
enough  to  enable  the  propeller  to  clear  the 
ground. 

Like  the  marine  turbine,  the  aerial  engine 
runs  too  fast  for  the  best  propeller  speeds. 
The  Wright  brothers  overcame  this  difficulty 
by  the  somewhat  unmechanical  expedient  of 
chain  gearing,  one  chain  being  crossed.  A 
French  firm  has  utilised  the  half-time  cam-shaft 
of  the  engine,  suitably  enlarged,  to  drive  the 
propeller,  thus  getting  a  speed  reduction  of  two 
to  one,  but  the  Bleriot,  Antoinette,  Farman, 
Voisin,  and  indeed  most  types  continue  to  drive 
the  propeller  directly  without  reduction.  It  is 
probable  that  the  direct  drive  will  prevail,  for 
any  form  of  gearing,  however  simple,  intro- 
duces an  element  of  risk  with  doubtful  benefits. 
At  present  there  is  scarcely  any  machine  which 


*io6    THE    NEW   ART   OF    FLYING 

has  the  propeller  well  under  control,  so  that  it 
can  be  stopped  and  started  and  altered  in  speed, 
without  stopping  the  motor.  This  is  due,  of 
course,  to  the  weight  of  clutches,  change-speed 
gears,  etc.  Probably  some  enterprising  engi- 
neer may  produce  a  suitable  gear  for  this  pur- 
pose before  long. 

In  this  outline  we  have  used  the  word  "  effi- 
ciency." How  is  efficiency  determined,  may 
well  be  asked.  The  true  efficiency  of  a  pro- 
peller driving  an  aeroplane  is  the  ratio  between 
the  work  of  propulsion  and  the  energy  con- 
sumed, the  work  of  propulsion  being  the  prod- 
uct of  the  travel  of  the  aeroplane  multiplied  by 
the  resistance  opposed  to  its  forward  move- 
ment. The  efficiency  is  measured  at  a  fixed 
point  by  causing  the  propeller  to  revolve,  with- 
out advancing  or  receding,  and  measuring  the 
thrust  produced,  in  the  direction  of  the  axis, 
by  a  given  horse-power. 

The  conditions  of  the  experiment  are  very 
different  from  those  of  rapid  flight  through  the 
air,  in  which  the  friction  between  the  air  and 
the  propeller  is  enormously  increased;  no  ac- 
count is  taken  of  the  resistance  opposed  by  the 


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THE    PROPELLER  107 

air  to  the  forward  movement  of  the  aeroplane. 
In  fact,  no  work  of  propulsion  is  performed  or 
even  imitated,  the  sole  result  being  a  thrust 
which  may  be  employed  for  propulsion.  Under 
these  conditions  the  propeller  is  comparable 
with  a  lever  which  supports  a  motionless  weight 
and  thus  exerts  a  stress,  but  performs  no  work. 
For  this  reason  absolute  reliance  cannot  be 
placed  on  the  results  of  many  propeller  tests. 

A  fair  imitation  of  the  conditions  of  flight 
as  they  directly  affect  the  propeller  itself  can 
be  obtained  by  placing  the  propeller  in  a  tube 
in  which  an  air  current  of  any  desired  velocity 
is  produced  by  blowers.  Some  experimenters 
mount  the  propeller  so  that  it  revolves  freely 
in  air  and  yet  drives  a  boat  or  a  road  vehicle. 

Some  of  the  best  results  obtained,  in  recent 
times,  of  thrust  for  horse-power  applied  are: 
Maxim,  nine  pounds;  Langley,  about  seven 
pounds;  Spencer  (with  a  Maxim  type  pro- 
peller), six  pounds;  Farman,  and  other  experi- 
menters in  France,  six  pounds  (about). 

It  is  now  a  widely  recognised  fact  that  the 
aerial  propellers  at  present  in  use  are  lament- 
ably inefficient.  Most  aeroplane  successes,  ex- 


io8    THE    NEW   ART    OF    FLYING 

cept  those  of  the  Wrights,  are  achieved  at  an 
enormous  cost;  for  the  propellers  waste  prob- 
ably more  than  half  the  power  applied. 

A  propeller  of  large  diameter  and  slow  revo- 
lution is  more  efficient  than  one  of  small  diam- 
eter and  high  speed,  a  circumstance  borne  out 
especially  in  the  case  of  the  Wright  machine, 
in  which  more  thrust  is  obtained  per  unit  of 
power  than  in  any  other  type  (Fig.  43). 

We  are  beginning  to  realise  that  the  abuse 
lavished  on  the  motor  should  be  bestowed  in 
very  large  measure  on  the  propeller.  The  in- 
ternal-combustion engine  fitted  to  the  aero- 
plane must  have  all  the  vital  parts  cut  to  the 
narrowest  margin,  and  must  be  worked  at  very 
nearly  break-down  rate  in  order  to  produce  an 
enormous  amount  of  surplus  power  wasted  by 
the  screw.  For  this  reason  all  our  more  serious 
investigators  are  carrying  out  scientific  experi- 
ments to  determine  propeller  efficiency.  Per- 
haps when  they  have  completed  their  work  we 
may  be  able  to  build  a  propeller  which  will 
drive  a  flying-machine  with  something  like  econ- 
omy of  power. 

The  construction  of  the  aerial  propeller  is 


THE    PROPELLER  109 

the  more  delicate,  because  it  depends  to  a  large 
extent  upon  the  peculiarities  of  the  vessel  to 
which  it  is  to  be  attached.  The  methods  em- 
ployed in  all  establishments  are  the  same;  yet 
a  Chauviere  propeller  is  very  different  from  a 
Wright  propeller. 


FIG.  42.  —  How  the  Wright  propeller  is  cut  from  three 
planks  laid  upon  one  another  fan-wise. 


A  Wright  propeller  is  made  of  American 
spruce  and  is  of  very  light  construction.  The 
extremities  of  the  blades  are  covered  with 
canvas,  which  is  varnished  with  the  rest,  for 
the  purpose  of  increasing  the  rigidity  of  the 
thin  outer  ends.  The  whole  propeller  is 
built  up  of  three  planks  arranged  as  shown  in 
Fig.  42,  so  that  they  overlap  like  the  sticks  of 
a  fan,  to  an  extent  which  diminishes  as  the  dis- 


no    THE    NEW   ART   OF    FLYING 

tance  from  the  hub  increases.  The  superfluous 
parts  of  the  wood,  represented  by  the  darker 
and  triangular  areas  of  the  upper  diagram  in 
Fig.  42,  are  then  cut  away,  and  the  curvature 
is  tested  at  every  point  by  patterns. 

Chauviere  propellers  are  made  of  ash,  fumed 
oak,  and  walnut,  and  include  six  or  seven  over- 
lapping planks.  The  finished  propeller  contains 
only  about  eight  and  one  half  per  cent  of  the 
wood  of  the  original  planks. 

It  should  be  added  that  constructors  show 
little  disposition  to  furnish  exact  details  of  their 
methods.  Their  industry  is  so  new  that  they 
jealously  guard  their  secrets,  for  which  reti- 
cence they  cannot  be  blamed. 

Propellers  are  also  made  of  metal.  In  these 
the  blades  are  soldered  or  riveted  to  the  arms, 
which  are  steel  tubes  riveted  to  the  hub.  The 
blades  are  shaped  by  hammering  them  upon  a 
form.  In  some  cases  they  are  cast,  or  twisted 
into  shape,  but  this  construction  is  not  so  good. 


CHAPTER   VIII 

AEROPLANE    MOTORS 

MARVEL  as  we  may  at  the  wonderful  ingenuity 
displayed  in  the  modern  flying-machine,  we  have 
still  much  to  learn  from  soaring  birds.  Little 
as  we  know  of  the  efficiency  of  curved  surfaces 
in  the  air,  we  know  still  less  how  to  drive  those 
surfaces  without  an  inordinate  expenditure  of 
power,  fuel,  and  lubricant.  We  have  only  to 
compare  the  amount  of  energy  expended  by  the 
great  flying  creatures  of  the  earth  with  that 
expended  by  our  machines  to  realise  how  much 
we  have  to  learn. 

The  late  Professor  Langley  long  ago  pointed 
out  that  the  greatest  flying  creature  which  the 
earth  has  ever  known  was  probably  the  extinct 
pterodactyl.  Its  spread  of  wing  was  perhaps 
as  much  as  twenty  feet ;  its  wing  surface  was  in 
the  neighbourhood  of  twenty-five  square  feet; 
its  weight  was  about  thirty  pounds.  Yet  this 
huge  creature  was  driven  at  an  expenditure  of 
energy  of  probably  less  than  0.05  horse-power. 


ii2    THE   NEW   ART   OF    FLYING 

The  condor,  which  is  preeminently  a  soaring 
bird,  has  a  stretch  of  wing  that  varies  from  nine 
to  ten  feet,  a  supporting  area  of  nearly  ten 
square  feet,  and  a  weight  of  seventeen  pounds. 
Its  approximate  horse-power  has  been  placed 
by  Professor  Langley  at  scarcely  0.05.  The 
turkey-buzzard,  with  a  stretch  of  wing  of  six 
feet,  a  supporting  area  of  a  little  over  five 
square  feet,  and  a  weight  of  five  pounds,  uses, 
according  to  Langley,  about  0.015  horse-power. 
Langley's  own  successful,  small,  steam-driven 
model  had  a  supporting  area  of  fifty-four  feet, 
and  a  weight  of  thirty  pounds.  Yet  it  required 
one  and  a  half  horse-power  to  drive  it.  How 
much  power  is  required  to  fly  at  high  speeds  in 
machines  may  be  gathered  from  the  fact  that 
although  Bleriot  crossed  the  Channel  with  a 
25  horse-power  Anzani  motor,  and  the  Wright 
machine  uses  a  25-30  horse-power  motor,  aero- 
planes usually  have  engines  of  50  horse-power 
and  upwards.  When  we  consider  that  one 
horse-power  is  equal  to  the  power  of  at  least 
ten  men,  we  see  that  even  the  smallest  power 
successfully  used  in  an  aeroplane  represents  the 
combined  continuous  effort  of  more  than  two 


AEROPLANE    MOTORS          113 

hundred  men.  To  be  sure,  our  flying-machines 
are  very  much  larger  than  any  flying  creature 
that  ever  existed;  but  comparing  their  weights 
and  supporting  surfaces  with  the  corresponding 
elements  of  a  bird,  their  relative  inefficiency  be- 
comes immediately  apparent.  Mr.  F.  W.  Lan- 
chester  has  expressed  the  hope  that  some  day 
we  may  learn  the  bird's  art  of  utilising  the  cur- 
rents and  counter-currents  of  the  air  for  propul- 
sion, so  that  we  may  ultimately  fly  without 
wasting  power. 

Aeroplanes  are  driven  by  what  are  known  as 
"  explosion  engines  "  or  "  internal  combustion 
engines."  The  fuel  is  not  used  externally,  as 
in  the  steam-engine,  but  is  fed  to  the  engine  in 
the  form  of  an  explosive  gas.  The  gas  is  det- 
onated within  the  engine  to  drive  a  piston. 
Most  of  these  internal  combustion  engines  oper- 
ate on  what  is  known  as  the  Otto  four  cycle. 
A  complete  cycle  comprises  four  distinct  pe- 
riods, which  are  diagrammatically  reproduced 
in  the  accompanying  drawings  (Figs.  49,  50, 
51,  and  52). 

During  the  first  period  (illustrated  in  Fig. 
49)  the  piston  is  driven  forward,  creating  a 


ii4    THE    NEW   ART   OF    FLYING 
vacuum  in  the  cylinder  and  simultaneously  draw- 
ing in  a  certain  quantity  of  air  and  gas.    During 


FIG.  49- 


FIG.  50. 


FIG.  52. 

FIGS.  49,  50,  51, -and  52.  — The  four  periods  of  a  four-cycle 
engine.  During  the  first  period  (Fig.  49)  the  explosive 
mixture  is  drawn  in;  during  the  second  period  (Fig.  50) 
the  explosive  mixture  is  compressed;  during  the  third 
period  (Fig.  51)  the  mixture  is  exploded;  and  during 
the  fourth  period  the  products  of  combustion  are  dis- 
charged. 


AEROPLANE    MOTORS          115 

the  second  period  the  piston  returns  to  its  initial 
position;  all  the  admission  and  exhaust  valves 
are  closed;  and  the  mixture  of  air  and  gas 
drawn  in  during  the  first  period  is  compressed. 
The  third  period  is  the  period  of  explosion. 
The  piston  having  reached  the  end  of  its  return 
stroke,  the  compressed  mixture  is  ignited  by  an 
electric  spark,  and  the  resulting  explosion  drives 
the  piston  forward.  During  the  fourth  period 
the  exploded  gases  are  discharged;  the  piston 
returns  a  second  time ;  the  exhaust  valve  opens ; 
and  the  products  of  combustion  are  discharged 
through  the  opened  valve.  These  various 
cycles  succeed  one  another,  passing  through  the 
same  phases  in  the  same  order. 

The  fuel  employed  in  the  internal  combustion 
engines  of  aeroplanes  is  gasoline,  called  petrol  in 
England,  which  is  volatilised,  so  that  it  is  sup- 
plied to  the  engine  in  the  form  of  vapour.  In 
order  that  it  may  explode,  this  vapour  is  mechan- 
ically mixed  with  a  certain  amount  of  air.  To 
obtain  what  is  called  cyclic  regularity  and  to  carry 
the  piston  past  dead  centres,  a  heavy  fly-wheel  is 
employed,  the  momentum  of  which  is  sufficient 
to  keep  the  piston  in  motion  on  the  return  stroke. 


n6    THE   NEW   ART   OF    FLYING 

Since  considerable  heat  is  developed  by  the 
incessant  explosions,  the  cylinders  naturally  be- 
come hot.  To  cool  them,  water  is  circulated 
around  them  in  a  "  water-jacket,"  or  else  a  fan 
is  used  to  blow  air  against  them. 

The  memorable  experiments  of  Professor 
Langley  on  the  Potomac  River  gave  rise  to  the 
idea  that  only  an  engine  of  extreme  lightness 
could  be  employed  if  the  flying-machine  was 
ever  to  become  a  reality.  Since  his  time  bi- 
planes have  lifted  three  and  four  passengers 
besides  the  pilot  over  short  distances.  While 
the  ultimate  achievement  of  dynamic  flight  was 
due  to  the  lightness  of  the  internal  combustion 
motor  in  relation  to  the  power  developed,  subse- 
quent experiment  has  demonstrated  how  the 
efficiency  of  the  sustaining  surfaces  can  be  in- 
creased so  as  to  diminish  head  resistance  and  to 
make  extreme  lightness  in  the  motor  desirable 
only  on  the  score  of  freight-carrying  capacity. 
The  original  motor  used  by  the  Wrights  was 
comparatively  heavy  for  the  power  developed. 

Saving  of  weight  in  the  motor  permits  the 
construction  of  a  more  compact  and  controllable 
machine  than  would  be  possible  if  the  sustain- 


Photograph  by  Edwin  Levick 

^y. — Gyrostat  mounted  in  an  aeroplane  accord- 
ing to  the  system  of  A.  J.  Roberts.    The  gyrostat 
is  controlled  by  a  pendulum  which  swings 
to  the  right  or  to  the  left,  according 
to  the  tilt  of  the  aeroplane 


AEROPLANE    MOTORS          117 

ing  surfaces  were  designed  to  carry  consider- 
able dead  weight.  To  gain  freight-carrying 
capacity  the  weight  of  the  motor  must  be  kept 
low.  The  fuel  needed  for  a  six-hour  flight,  for 
example,  is  equal  in  load  to  an  engine  weighing 
three  pounds  per  brake  horse-power,  assuming 
that  the  hourly  fuel  consumption  is  one  half  a 
pound  per  horse-power.  Clearly  the  motor 
must  be  light  if  the  flight  is  to  be  long. 

There  are  various  ways  of  securing  lightness 
in  a  motor.  One  way  is  to  increase  the  power 
developed  by  cylinders  of  a  certain  size.  An- 
other is  to  reduce  the  weight  for  a  given  cylin- 
der capacity  by  the  use  of  thin  steel  cylinders 
and  by  constructing  the  parts  as  lightly  as  pos- 
sible. A  third  way  is  to  arrange  the  cylinders 
in  such  a  manner  that  more  than  one  connect- 
ing-rod is  assigned  to  each  crank  with  a  conse- 
quent reduction  in  the  weight  of  the  crank- 
case.  A  fourth  way  is  to  cool  the  cylinders 
with  air  instead  of  water. 

Many  motor  builders  have  abandoned  the 
fly-wheel  because  it  is  the  heaviest  part  of  the 
engine.  In  order  that  the  motor  may  run 
steadily  without  a  fly-wheel  and  may  be  prop- 


n8    THE    NEW   ART    OF    FLYING 

erly  balanced,  it  has  been  necessary  to  rearrange 
the  cylinders  and  to  increase  their  number. 
The  whole  subject  was  recently  considered  by 
an  anonymous  writer  in  Engineering  (London) . 
The  following  lucid  paragraphs  on  the  arrange- 


FIG.  53.  —  The  usual  arrangement  of  the  four  cylinders  of 
a  four-cylinder  engine. 

ment  of  cylinders  in  present  aeroplane  motors 
present  his  views: 

*  The  weight  of  an  engine  consists  princi- 
pally of  the  cylinders  and  pistons  on  the  one 
hand,  and  the  crank,  crank  shaft,  etc.,  on  the 
other.  Roughly  speaking,  the  weight  of  the 
cylinders  will  be  proportionate  to  the  cube  of 
the  dimensions.  That  is  to  say,  if  the  cylinders 
are  arranged  vertically  in  a  row,  for  instance, 
the  weight  of  the  crank  case,  shaft,  etc.,  will  be 
practically  proportionate  to  the  cylinder  ca- 


AEROPLANE    MOTORS         119 

pacity.  If  we  can  mount  the  cylinders  in  such 
a  manner  that  we  can  get  a  great  cylinder  ca- 
pacity with  a  very  short  crank  case,  we  shall, 
however,  save  weight.  If,  for  instance,  we  start 
with  the  vertical  four-cylinder  engine  of  the  or- 
dinary type,  as  shown  in  Fig.  53,  the  crank  case 
has  necessarily  to  be  as  long  as  the  length  over 
the  cylinders.  In  this  and  the  following  figures 
the  valves  are  omitted  for  the  sake  of  clearness, 
and  in  all  the  figures  the  cylinders  are  the  same 
size,  so  that  the  size  of  crank  case  necessary  for 
a  given  cylinder  capacity  can  easily  be  seen. 

'*  Two  common  plans  for  reducing  the  length 
and  weight  of  the  crank  case  are  to  place  the 
cylinders  either  diagonally,  as  in  Figs.  54  and 
55,  or  horizontally  opposed,  as  in  Fig.  56.  In 
either  of  these  arrangements  the  length  of  the 
crank  case,  etc.,  is  almost  halved,  and  a  consid- 
erable saving  of  weight  is  effected.  Any  of 
these  arrangements  can  be  made  with  two,  four, 
six,  eight,  or  more  cylinders.  In  the  case  of  the 
diagonal  engine  the  impulses  are  not  evenly 
divided  with  two  or  four  cylinders,  though  they 
can  be  so  with  six,  if  the  angle  between  the  cyl- 
inders be  made  one  hundred  and  twenty  degrees. 
With  eight  cylinders  at  ninety  degrees  the  im- 
pulses are  evenly  divided,  and  this  is  the  most 
usual  number.  In  this  type  each  diagonal  pair 
of  cylinders  is  connected  with  one  crank.  The 


120    THE    NEW   ART   OF    FLYING 

diagonal  engine,  with  the  cranks  at  ninety  de- 
grees, can  be  balanced  for  all  practical  purposes, 
even  where  there  are  only  two  cylinders,  by 
placing  a  balance  weight  opposite  the  crank 


FIGS.  54  and  55.  —  Side  and  plan  views  of  a  four-cylinder 
engine  with  diagonally-placed  cylinders. 

equal  to  the  weight  of  the  whole  rotating  parts 
and  the  reciprocating  parts  of  one  cylinder. 
With  four  cylinders  the  cranks  are  usually 
placed  opposite,  but  balance  weights  are  still 
necessary  to  avoid  a  rocking  moment.  With 
eight  cylinders  the  cranks  are  set  so  that  the  two 


AEROPLANE    MOTORS 

end  ones  are  opposite  the  two  middle  ones,  and 
no  balance  weights  are  required. 

"  In  the  case  of  the  opposed  horizontal  en- 
gine the  two  connecting  rods  work  on  opposed 


FIG.  56 


FIG.  57. 

FIGS.    56    and    57.  —  Engine    with    horizontally    opposed 
cylinders. 

cranks,  as  in  Fig.  57.  In  this  case  the  engine, 
even  the  two-cylinder,  is  in  many  ways  better 
balanced  than  the  vertical  or  diagonal  types,  as 
the  error  in  balancing,  due  to  the  angle  of  the 
connecting  rods,  is  allowed  for.  If  only  two 
cylinders  are  used,  there  is,  however,  a  very 


122    THE    NEW   ART   OF    FLYING 

small  rocking  moment,  due  to  the  fact  that  the 
cylinders  are  not  actually  opposite  each  other; 
but  this  is  usually  a  negligible  quantity.  .  .  . 
With  four  cylinders  the  rocking  moment  is  bal- 
anced. The  impulses  in  the  horizontal  opposed 
engine  are  always  evenly  divided,  whether  two, 
four,  or  eight  cylinders  are  used. 

"  Comparing  the  horizontal  opposed  with  the 
diagonal  engine,  the  former  appears  to  have  all 
the  advantages,  as  the  impulses  are  more  even 
with  a  small  number  of  cylinders,  and  the  bal- 
ance better.  The  latter  point  will  enable  some- 
what shorter  connecting  rods  to  be  used  with- 
out excessive  vibration,  thus  lightening  the 
engine.  .  .  . 

'*  While  the  crank  case,  etc.,  is  distinctly 
lightened  by  these  arrangements,  it  can  be  still 
more  reduced  if  the  cylinders  are  all  arranged 
radially  on  to  one  crank.  This  has  been  done 
in.  a  great  many  different  ways  by  different 
makers.  For  comparison,  with  the  previously- 
mentioned  four-cylinder  engines,  a  four-cylinder 
radial  engine  is  shown  in  Figs.  58  and  59,  the 
cylinders  being  the  same  size  as  before.  It  will 
be  seen  that  in  this  case  the  crank  case  and  shaft 
are  very  much  shorter  and  lighter  than  in  any  of 
the  previous  arrangements.  In  practice  four  is 
not  a  good  number  of  cylinders,  as  the  impulses 
cannot  be  evenly  divided,  and  an  odd  number 


AEROPLANE    MOTORS          123 

of  cylinders  must  be  used  to  effect  this.  This 
type  of  engine  can  be  satisfactorily  balanced  as 
long  as  the  cylinders  are  evenly  spaced  round 
the  crank  case,  for  all  the  pistons  are  attached 


FIG.  58 


FIGS.   58  and   59.  —  Engine   with    four   cylinders   radially 
arranged. 

to  one  crank  pin,  and  therefore  form  one  revolv- 
ing weight,  which  can  be  balanced  by  a  suitable 
balance  weight. 

'  When  many  cylinders  are  used  it  is  imprac- 
ticable actually  to  put  all  the  connecting  rods 
to  work  onto  one  crank  pin,  as  either  the  big 


124    THE   NEW   ART   OF    FLYING 

ends  would  have  to  be  very  narrow,  or  the  crank 
pin  impracticably  long.  This  can,  however,  be 
got  over  by  the  arrangement  shown  in  Fig.  60. 

"  Probably  the  greatest  difficulty  in  making 
the  radial  engine  satisfactory  is  that  of  lubrica- 


FIG.  60.  —  Arrangement  of  connecting-rods  of  an  engine 
with  four  radial  cylinders. 


tion.  This  is  a  matter  which  does  not  seem  to 
have  had  nearly  as  much  attention  paid  to  it  as 
it  needs.  .  .  .  The  even  distribution  of  the  oil 
to  the  various  cylinders  of  a  radial  engine  is 
very  difficult,  and  further,  however  well  it  might 
be  managed  when  the  engine  is  running,  as  soon 
as  it  stops  the  oil  runs  into  the  lower  cylinders, 
and  probably  fouls  the  plugs,  so  that  it  is  diffi- 


AEROPLANE    MOTORS          125 

cult  to  start  it  again.  In  order  to  get  over  this, 
the  engine  has  occasionally  been  mounted  on  its 
side,  with  the  crank  shaft  vertical,  the  propeller 
being  driven  through  bevel  gear.  If  it  is  desired 
to  run  the  propeller  slower  than  the  engine,  there 
is  no  great  objection  to  this,  and  there  is  little 
doubt  that  the  slow-running  propeller  is  much 
the  more  efficient.  Another  plan  is  to  mod- 
ify the  arrangement  of  the  cylinders.  Thus  in 


FIG.  61.  —  Arrangement  of  cylinders  and  crank  case  of  one 
type  of  three-cylinder  engine. 

one  make  of  three-cylinder  engine  the  cylinders 
are  all  at  the  top  of  the  crank  case  (Fig.  61), 
all  the  connecting  rods  leading  to  one  crank  pin. 
In  this  case  it  is  impossible  to  divide  the  im- 
pulses evenly,  and  the  balancing  is  not  so  good. 
In  practice  this  type  of  engine  is  made  with  in- 
side fly-wheels  of  considerable  weight,  and  runs 
well,  but  the  fly-wheels  necessarily  add  to  the 


126    THE    NEW   ART    OF    FLYING 

weight.  Another  plan  is  to  put  all  the  cylinders 
at  the  top  of  the  crank  case,  and  to  place  those 
which  should  have  been  at  the  bottom  in  a  com- 
plete radial  engine  on  a  crank  opposite  to  the 
others,  as  shown  in  Fig.  62. 

"  In  some  cases  the  radial  engine  is  made 
with  the  crank  shaft  fixed  and  the  cylinders  re- 
volving. As  constructed  by  the  Societe  des 
Moteurs  Gnome,  this  type  (Fig.  46)  has  given 
very  good  results,  but  it  may  be  doubted 


FIG.  62.  —  Disposition  of  cylinders  crank  case  and  connect- 
ing-rods in  one  type  of  engine. 


whether  they  are  due  simply  to  making  the  cyl- 
inders revolve.  A  very  small  amount  of  con- 
sideration will  show  that  the  radial  engine  will 
be  of  the  same  weight  whether  the  cylinders  re- 
volve or  the  crank  shaft,  all  other  details  of 
construction  being,  of  course,  assumed  to  be 
the  same.  This  being  so,  the  only  way  in  which 


AEROPLANE    MOTORS          127 

the  revolving  cylinders  can  be  an  advantage  is 
either  by  obtaining  a  lighter  construction  of 
cylinder  or  crank  case,  or  else  by  increasing  the 
power  obtained  from  a  given  sized  cylinder. 
There  does  not  seem  any  reason  for  supposing 
that  revolving  the  cylinders  secures  either  of 
these  results. 

'*  The  advantages  of  the  revolving  cylinders 
are :  ( i )  That  they  act  as  a  fly-wheel,  and  ( 2 ) 
that  they  render  air-cooling  more  efficient. 
Where  the  propeller  is  directly  coupled,  how- 
ever, no  fly-wheel  is  required  in  any  case.  No 
doubt  there  is  a  distinct  advantage  in  the  air- 
cooling  from  the  fact  that  the  cylinders  revolve, 
but  it  is  not  likely  to  be  very  great. 

"  Assuming  that  the  ends  of  the  cylinders  are 
fifteen  inches  from  the  crank  shaft,  and  the 
engine  runs  at  twelve  hundred  revolutions  per 
minute,  the  ends  of  the  cylinders  move  through 
the  air  at  about  ninety-five  miles  an  hour. 
When  the  engine  with  fixed  cylinders  is  placed 
just  behind  the  propeller,  it  probably  always 
works  in  a  current  of  air  moving  sixty  miles  an 
hour  or  more,  so  it  will  be  seen  that  the  differ- 
ence is  not  so  great  as  might  be  expected.  In 
practice  the  power  given  per  cubic  inch  of  cylin- 
der capacity  by  the  Gnome  engine  is  very  small, 
and  there  seems  no  reason  to  doubt  that  the 
same  power  could  be  obtained  from  fixed  cylin- 


128    THE   NEW   ART   OF    FLYING 

ders  of  smaller  size.  The  good  results  appear 
to  be  due  to  the  fact  that  the  weight  of  the  parts 
is  reduced  by  machining  practically  all  parts,  in- 
cluding the  cylinders  and  crank  case,  from  steel 
forgings  to  such  an  extent  that  the  engine 
weighs  only  0.35  pounds  per  cubic  inch  of  cyl- 
inder capacity.  It  seems  probably  that  with 
fixed  cylinders  at  least  equally  good  results 
could  be  obtained  if  the  same  amount  of  trouble 
and  money  were  spent." 


The  prime  difficulty  with  the  radial  rotating 
engine  shown  in  Fig.  46  is  the  lubrication,  and 
until  some  means  of  reducing  the  consumption 
of  lubricating  oil  is  devised,  the  rotating  cylin- 
der motor  must  have  at  least  that  compensat- 
ing defect.  On  occasions  such  as  a  flight  from 
Chicago  to  New  York  for  a  prize  the  use  of 
large  quantities  of  lubricating  oil  may  not  mat- 
ter, but  in  an  everyday  motor  for  the  aeroplane 
in  the  hands  of  the  "  chauffeur,"  or  whatever 
his  aerial  equivalent  may  be  called,  the  lubri- 
cation must  be  relied  upon  more  than  in  the 
motor  car;  for  while  failure  in  the  one  case 
means  only  inconvenience,  in  the  other  it  may 
entail  disaster. 


AEROPLANE    MOTORS          129 

The  horse-power  required  for  flight  varies  to 
a  certain  extent  as  the  speed.  Hence  the  factor 
that  governs  the  maximum  velocity  of  flight  is 
the  horse-power  that  can  be  developed  on  a 
given  weight.  At  present  the  weight  per  horse- 
power of  featherweight  motors  appears  to  range 
from  two  and  one  quarter  up  to  seven  pounds 
per  brake  horse-power.  A  few  actual  figures 
are  given  in  the  following  list : 

Antoinette  5  Ibs.  per  brake  horse-power. 

Fiat  3    "      " 

Gnome  under  3  Ibs. 

Metallurgic  8  Ibs. 

Renault  7    " 

Wright  6    " 

Automobile  engines,  on  the  other  hand,  com- 
monly weigh  12  pounds  to  13  pounds  to  the 
brake  horse-power. 

Because  lightness  and  durability  are  oppo- 
site qualities,  and  because  the  more  trustworthy 
a  machine  must  be,  the  heavier  must  be  its  con- 
struction, it  may  well  be  inferred  that  the  aero- 
plane motor  is  not  a  model  either  of  durability 
or  trustworthiness.  The  aeroplane  builder  ap- 


130    THE    NEW   ART   OF    FLYING 

pears,  at  present,  willing  to  tolerate  very  little 
reliability,  largely  because  the  aeroplane  is  still 
in  the  hands  of  record-breakers  and  prize- 
winners, rather  than  of  ordinary  tourists.  In 
making  records  the  start  takes  place  when  the 
motor  is  ready.  In  a  race  it  takes  place  at  some 
determinate  time,  and  if  the  motor  be  not  ready, 
then  the  chance  is  lost.  The  record  is  also  the 
result  of  frequent  trials;  a  race  is  gained  or 
lost  in  one.  Thus,  if  one  motor  will  make  an 
aeroplane  fly  fifty  miles  whenever  required  and 
without  unreasonable  tuning  up,  but  another 
makes  it  fly  one  hundred  miles  once  out  of  ten 
attempts,  the  latter  takes  the  record,  though  on 
its  nine  failures  it  may  have  broken  down  in  a 
few  miles,  and  may  have  required  hours  tuning 
up  for  each  trial.  If,  however,  the  aeroplane 
is  ever  to  be  of  the  slightest  practical  use,  the 
reliability  of  the  engine  must  not  only  be 
brought  up  to  that  of  the  racing  machine,  but 
very  much  beyond  it.  This  lack  of  reliability 
was  strikingly  evinced  in  the  famous  Circuit 
de  I'Est  of  1910,  a  circular  cross-country  race 
which  started  from  Paris  and  finished  there,  and 
which  included  the  towns  of  Troyes,  Mezieres, 


AEROPLANE    MOTORS         131 

Douai,  and  Amiens.  The  contest  was  remark- 
able because  the  airmen  were  expected  to  per- 
form what  they  had  never  attempted  before. 
They  had  to  fly  over  a  given  course  on  specified 
days  without  being  able  to  choose  weather  con- 
ditions most  favourable  to  them.  Eight  ma- 
chines started  from  Paris,  but  after  the  second 
day  the  only  competitors  left  were  Leblanc  and 
Aubrun  on  their  Bleriot  monoplanes.  The  fail- 
ures of  the  others  were  due  solely  to  engine 
troubles. 

A  resume  of  aeroplane  motors  compiled  by 
Warren  H.  Miller  is  appended  below  in  the 
concise  form  of  a  table  of  comparative  costs 
and  weights  per  horse-power  based  on  the  fifty 
horse-power  size.  It  will  be  noticed  that  the 
Clement-Bayard  is  by  far  the  heaviest,  in  spite 
of  using  aluminium  for  the  case,  thus  adding  to 
the  already  large  amount  of  proof  that  for  equal 
strength  steel  is  always  lighter  than  aluminium. 
The  table  also  brings  out  the  increased  cost  ne- 
cessitated by  multiplication  of  cylinders,  to  ob- 
tain increased  horse-powers  at  light  weights. 
The  Anzani,  with  only  three  cylinders,  is  by  far 
the  cheapest,  but  its  weight  is  about  midway  be- 


i32    THE   NEW   ART   OF    FLYING 

tween  the  Clement  and  the  Gnome,  the  lightest 
of  them  all. 

TABLE  OF  FRENCH  AVIATION  MOTORS 

Make               H.  P.  Weight  per  h.  p.  Cost  per  h.  p.     Speed. 

Antoinette     ...  50  3 -84  Ibs.  $48.00  ,200 

Anzani 50  4.6    Ibs.  20.00  ,400 

Gnome 50  3-3<5  Ibs.  52.00  ,200 

E.  N.  V 40  3-85  Ibs.  37.50  ,500 

Clement-Bayard     40  6.05  Ibs.  47.50  ,500 

R.  E.  P 40  3.96  Ibs.  70.00  ,500 

Wright 25  7-2    Ibs.  


CHAPTER   IX 

THE   NEW  SCIENCE   OF  THE  AIR 

So  far  as  the  earth  is  concerned,  the  sun  is  very 
much  in  the  position  of  a  man  who  practically 
utilises  only  a  single  cent  out  of  a  fortune  of 
$22,000,000  and  throws  the  rest  away;  for  only 
1/2,200,000,000  of  the  sun's  heat  ever  reaches 
us.  That  pittance  must  be  conserved,  for  which 
reason  the  earth  is  wrapped  in  a  wonderful, 
transparent,  and  invisible  garment  which  we  call 
the  air  and  which  serves  the  very  utilitarian  pur- 
pose of  keeping  the  world  warm.  Of  the  thick- 
ness of  that  wrapping  we  know  but  little.  Per- 
haps it  may  extend  outward  from  the  earth  for 
a  distance  of  two  or  three  hundred  miles  if  we 
may  judge  from  observations  of  meteor  trains 
and  auroras.  Some  idea  of  its  depth  may  be 
gained  by  stating  that  if  this  planet  were  a 
globe  only  six  feet  in  diameter,  the  air  would  be 
not  much  more  than  two  inches  thick.  The  tex- 
ture of  this  gaseous  garment  and  its  peculiar 
relation  to  the  sun  have  but  recently  been  made 


134  THE  NEW  ART  OF  FLYING 
the  subject  of  rigorous  investigation;  for  only 
in  our  own  day  has  it  been  perceived  that  the 
vagaries  of  the  weather  may  thus  be  satisfac- 
torily explained  and  a  system  of  weather  fore- 
casting devised  more  far-reaching  and  accurate 
than  that  which  at  present  serves  us. 

One  step  in  this  investigation  is  the  study  of 
the  physical  attributes  with  which  the  air  is  en- 
dowed. The  air  has  a  weight  which  fluctuates 
from  day  to  day  and  from  hour  to  hour.  It  is 
sometimes  warm  and  sometimes  cold,  sometimes 
moist  and  sometimes  dry,  sometimes  calm  and 
sometimes  turbulent.  All  this  our  senses  taught 
us  long  ago.  But  so  crude  are  our  senses  that 
they  can  never  tell  us  exactly  how  much  it  weighs 
at  a  given  moment,  how  wet  it  is,  how  fast  it 
moves,  and  how  warm  or  cold  it  is.  The  physi- 
cist has,  therefore,  been  constrained  to  devise 
subtler  senses.  He  has  given  us  a  remarkable 
balance  which  is  known  to  every  one  as  a  barom- 
eter and  which  weighs  the  air  to  a  nicety;  a  del- 
icate measurer  of  moisture,  which  he  calls  a 
hygrometer ;  a  motion  or  wind  recorder,  known 
as  an  anemometer;  and  a  heat-measurer  in  the 
form  of  the  familiar  thermometer.  These  re- 


THE  NEW  SCIENCE  OF  THE  AIR    135 

sponsive  artificial  senses  have  been  used  on  the 
surface  of  the  earth  for  many  years,  and  by 
their  means  are  gathered  the  main  facts  upon 
the  basis  of  which  the  weather  bureaus  at 
home  and  abroad  venture  to  predict  the  mor- 
row's weather. 

Because  we  have  learned  practically  all  there 
is  to  learn  of  the  lower  air  and  because  weather 
forecasters  have  in  the  past  ignored  the  upper 
levels  of  the  air,  levels  which  unquestionably 
have  their  influence  on  the  weather,  it  was  felt 
that  some  effort  must  be  made  to  measure  the 
thickness  of  the  earth's  invisible  wrapping  and 
to  determine  the  weight,  temperature,  velocity, 
and  moisture  of  the  air  miles  above  us. 

In  order  to  accomplish  this  task  it  was  essen- 
tial to  invent  an  artificial  arm  which  would 
grasp  the  sensitive  barometer,  thermometer, 
hygrometer,  and  anemometer  devised  by  the 
physicist  and  hold  them  for  us  in  the  upper 
reaches  of  the  air.  The  problem  of  providing 
such  an  arm  was  not  easily  solved.  In  fact,  it 
is  not  completely  solved  even  now,  for  which 
reason  the  hand  of  science  has  not  yet  suc- 
ceeded in  touching  the  uppermost  layer  of  air 


136    THE    NEW   ART   OF    FLYING 

—  the  hem  of  the  earth's  mysterious  robe. 
Meteorological  observations  with  manned  bal- 
loons have  been  made  sporadically  for  much 
more  than  a  century.  An  ascent  was  made  by 
Jeffries,  at  London,  in  1784,  with  a  remarkably 
complete  equipment  of  meteorological  appara- 
tus. Hardly  a  year  passes  but  that  experiment 
is  repeated.  Because  a  human  being  cannot 
breathe  the  tenuous  air  of  great  altitudes  and 
live,  the  experiment  has  sometimes  proved 
fatal.  To  overcome  the  difficulty,  the  meteor- 
ologist has  torn  a  leaf  from  the  book  of  the 
marine  biologist,  who  plumbs  the  deep  sea  with 
scientific  instruments  and  brings  to  the  surface 
living  facts  for  subsequent  study.  The  meteor- 
ologist, accordingly,  now  sounds  the  air,  as  if  it 
were  a  great  invisible  ocean  at  the  bottom  of 
which  we  live. 

The  artificial  arm  that  reaches  upward  has 
assumed  the  form  either  of  a  kite  or  of  a  small 
unmanned  balloon,  and  thus  it  has  become  pos- 
sible to  elevate  to  great  heights  the  mechanical 
senses  that  weigh  the  air,  feel  its  moisture  and 
its  heat,  and  note  its  motion.  The  men  to 
whom  most  of  the  credit  is  due  for  all  that  has 


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THE  NEW  SCIENCE  OF  THE  AIR    137 

been  gleaned  in  the  last  few  years  are  Teis- 
serenc  de  Bort,  of  France,  Prof.  A.  Lawrence 
Rotch,  of  the  United  States,  and  Dr.  Richard 
Assmann,  of  Germany. 

During  the  past  decade  the  work  has  been 
taken  up  by  the  official  meteorological  services 
of  the  world,  and  is  now  carried  on  systemati- 
cally under  the  direction  of  an  international 
commission,  appointed  by  the  International 
Meteorological  Committee.  This  commission 
has  a  permanent  office  at  Strassburg,  and  holds 
triennial  meetings  in  different  cities,  in  which 
meteorologists  from  all  civilised  countries  par- 
ticipate. The  next  meeting  will  take  place  at 
Vienna,  in  1912. 

In  the  United  States,  in  addition  to  the  ad- 
mirable work  done  at  Blue  Hill,  by  Professor 
Rotch  and  his  staff,  regular  observations  of  the 
upper  air  are  carried  on  by  the  Weather  Bureau 
at  the  Mt.  Weather  Observatory,  near  Blue- 
mont,  Va.,  and  the  data  obtained  are  tele- 
graphed daily  to  Washington,  for  the  informa- 
tion of  the  official  weather-forecasters. 

In  Europe  there  are  now  several  institutions 
devoted  entirely  to  this  branch  of  investiga- 


138    THE    NEW   ART   OF    FLYING 

tions.  The  most  elaborate  of  these  is  the  Royal 
Prussian  Aeronautical  Observatory  at  Linden- 
berg,  not  far  from  Berlin,  and  Germany  has  ob- 
servatories of  similar  character,  on  a  somewhat 
smaller  scale,  at  Hamburg,  Aachen,  Friedrichs- 
hafen,  and  elsewhere.  The  observatory  at 
Friedrichshafen  is  unique  in  possessing  a  small 
steamboat  which  plies  the  waters  of  Lake  Con- 
stance and  is  especially  equipped  for  sending  up 
kites  and  balloons.  Other  "  aerological  obser- 
vatories, "  as  the  institutions  of  this  character  are 
now  called,  are  situated  at  Trappes,  near  Paris ; 
Pavia,  Italy;  and  Pavlovsk,  Russia;  while  in 
the  British  Isles  the  chief  centre  for  aerological 
observations  is  the  Glossop  Moor  Observatory, 
near  Manchester.  Similar  observatories  exist 
in  subtropical  regions,  in  Egypt  and  India.  A 
very  important  station  is  located  on  the  peak 
of  Teneriffe,  in  the  Canary  Islands.  In  the 
southern  hemisphere  upper-air  researches  are 
now  regularly  carried  on  at  two  places,  viz., 
in  Samoa;  and  at  Cordoba,  in  the  Argentine 
Republic.  In  addition  to  these  fixed  observa- 
tories, mention  should  be  made  of  the  aero- 
logical work  now  frequently  carried  out  by  ex- 


THE  NEW  SCIENCE  OF  THE  AIR    139 

ploring  expeditions,  especially  in  the  polar 
regions. 

The  scientific  projection  of  the  human  mind 
to  the  upper  atmosphere  was  not  achieved 
merely  by  the  invention  of  instruments  and 
means  for  elevating  them.  Our  eyes  could  not 
read  the  instruments  when  they  were  suspended 
in  the  air,  and  so  it  became  necessary  to  make 
the  artificial  senses  self-recording.  Ingenious 
scientific  artisans  have  provided  the  barometer, 
thermometer,  hygrometer,  and  wing-gauge  with 
clock-driven  fingers  that  write  a  continuous, 
colourlessly  impersonal,  and  therefore  unbiassed 
story  of  atmospheric  happenings  at  great 
heights,  —  a  story  which,  to  those  who  are 
versed  in  the  hieroglyphic  script  in  which  it  is 
written,  gives  a  coherent  account  of  the  condi- 
tions that  prevail  at  various  elevations.  The 
unselfish  inventive  genius  which  has  been  dis- 
played in  devising  these  self-recording  instru- 
ments would  have  been  richly  rewarded  had  it 
been  applied  to  the  needs  of  every-day  life. 

The  lifting  power  of  kites  and  balloons  is 
limited,  for  which  reason  the  instruments  are 
made  of  feathery  lightness  and  are  ingeniously 


i4o    THE    NEW   ART   OF    FLYING 

combined.  The  combination  is  generically 
known  as  a  "  meteorograph."  Thus  the  ther- 
mometer and  barometer  are  merged  into  a 
meteorograph  specifically  known  as  a  "  baro- 
thermograph,"  a  contrivance  which  is  provided 
with  two  automatic  hands,  one  of  which  writes 
down  the  weight  (pressure)  of  the  air  and  the 
other  its  temperature.  Sometimes  the  barom- 
eter, thermometer,  and  hygrometer  are  joined 
in  a  single  instrument,  which  notes  the  humidity 
as  well  as  the  pressure  and  temperature.  When 
the  instruments  return  to  the  ground,  their 
records  inform  the  meteorologist  of  the  height 
of  the  kite  or  balloon  at  any  given  minute 
during  its  ascent  and  of  the  temperature  and 
barometric  pressure  at  that  particular  minute. 
Because  no  ink  has  been  found  which  will  not 
freeze  in  the  bitter  cold  of  the  upper  air,  the 
writing  fingers  of  these  instruments  trace  their 
story  on  smoked  cylinders.  At  lower  levels 
special  inks  and  paper  can  be  employed.  Sam- 
ples of  air  have  been  collected  by  Teisserenc  de 
Bort  at  heights  which  no  human  being  can  ever 
hope  to  reach,  by  devices  that  operate  as  if  they 
were  endowed  with  brains.  To  explain  this 


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THE  NEW  SCIENCE  OF  THE  AIR    141 

remarkable  feat,  it  may  be  stated  that  at  a  pre- 
determined altitude  the  barometer  was  made 
to  complete  an  electric  circuit  (just  as  we  push 
a  bell-button),  whereupon  a  little  hammer  fell 
and  broke  a  closed,  exhausted  glass  tube.  Air 
rushed  into  the  tube,  and  the  glass  was  there- 
upon automatically  sealed  by  a  current  which 
heated  a  platinum  wire  coiled  around  the  broken 
end  of  the  tube,  thereby  fusing  the  glass. 

These  are  but  a  few  of  a  long  list  of  scien- 
tific inventions  which  might  be  cited  and  of 
which  the  world  hears  nothing.  Meteorology 
has  more  than  one  unheralded  Edison  and 
Tesla,  men  who  labour  year  after  year  in  scien- 
tific obscurity,  and  who  deem  themselves  richly 
rewarded  if  their  instruments  aid  in  the  dis- 
covery of  some  new  atmospheric  phenomenon 
which  may  illumine  the  very  dark  subject  of 
meteorology. 

The  elevation  of  these  instruments  by  kites 
has  probably  been  carried  to  the  greatest  per- 
fection by  Prof.  A.  Lawrence  Rotch,  of  the  Blue 
Hill  Meteorological  Observatory  at  Hyde  Park, 
Massachusetts.  His  exploration  of  the  lower 
four  miles  of  air  is  the  most  complete  that  has 


I42    THE    NEW   ART   OF    FLYING 

yet  been  made.  The  kites  employed  by  him, 
and,  for  that  matter,  by  most  air  explorers,  are 
of  the  open  box  type,  which  every  boy  now 
flies  in  preference  to  the  old-fashioned  single- 
surface  contrivance  distinguished  by  its  long  tail 
of  rags  knotted  together.  For  meteorological 
purposes,  however,  the  box  kite  assumes  dimen- 
sions that  utterly  dwarf  its  toy  prototype.  Some 
of  the  Blue  Hill  kites  measure  nine  feet  in 
length.  Despite  the  great  lifting  capacity  im- 
parted by  its  expansive  surface,  an  air-exploring 
kite  could  not  attain  a  considerable  height 
if  it  were  held  only  by  hemp.  A  cord  or 
rope  would  necessarily  be  so  heavy  and  thick 
that  a  kite  would  be  severely  taxed  in  pulling  it 
up.  Hence  it  is  the  practice  to  employ  fine 
piano-wire,  which  is  both  strong  and  light. 

So  powerful  is  the  pull  of  a  large  kite  that 
human  muscles  are  hardly  able  to  cope  with  it. 
An  engine-driven  winch  is  therefore  utilised  to 
haul  in  the  long  line.  Devices  are  employed 
to  register  the  pull  of  the  kite  and  the  length 
of  the  wire  in  use.  Often  it  happens  that  as 
much  as  ten  miles  of  line  may  be  paid  out. 
The  elevation  of  the  kite  is  determined  in  clear 


THE  NEW  SCIENCE  OF  THE  AIR    143 

weather  from  data  obtained  by  means  of  special 
optical  instruments  (theodolites)  placed  on  the 
ground.  At  night  and  in  hazy  weather  the 
meteorograph  readings  themselves  must  be 
depended  upon. 

Four  miles  may  be  considered  the  maximum 
height  that  a  kite  is  capable  of  attaining.  To 
explore  the  air  above  that  limit  and  above  the 
six  miles  that  mark  the  end  of  human  endurance 
in  manned  balloons,  the  "  sounding-balloon " 
is  employed,  of  which  the  most  skilful  use  has 
been  made  by  Teisserenc  de  Bort  and  by  Dr. 
Richard  Assmann. 

The  balloons  are  filled  with  hydrogen  gas, 
which  expands  with  increasing  elevation.  The 
degree  of  inflation  therefore  depends  upon  the 
height  to  be  attained.  Thus,  if  the  balloon  is 
to  reach  a  point  where  the  air  is  one  half  as 
dense  as  it  is  at  the  level  of  the  sea,  the  gas- 
bag is  half  filled.  If  at  the  objective  point  the 
density  of  the  air  is  one  fourth  the  density  at 
the  level  of  the  sea,  the  bag  is  filled  only  one 
fourth.  Obviously,  if  very  great  heights  are 
to  be  attained,  heights  where  the  air  is  exceed- 
ingly rare  and  thin,  the  balloon's  capacity  must 


i44    THE    NEW   ART    OF    FLYING 

be  great  and  the  construction  wonderfully  light. 
Paper  balloons  were,  therefore,  adopted  by 
Teisserenc  de  Bort.  Latterly,  however,  Ass- 
mann's  India-rubber  balloons,  varying  in  diam- 
eter from  three  to  five  feet,  have  come  into  use, 
because  they  reach  greater  heights.  At  the 
maximum  elevation  of  the  balloon  the  expansion 
of  the  hydrogen  gas  is  so  powerful  that  the 
balloon  bursts.  Retarded  in  their  fall  by  a  para- 
chute, the  instruments  glide  gently  down  to  the 
ground.  Instead  of  a  parachute  a  slightly 
inflated  auxiliary  balloon  may  be  employed 
which  does  not  explode,  and  which  has  sufficient 
buoyancy  to  prevent  a  too  rapid  descent  of  the 
instruments  and  to  indicate  the  position  of  the 
basket  in  a  thicket  or  at  sea.  To  the  basket 
in  which  the  instruments  are  contained  a  printed 
notice  is  attached  which  offers  a  reward  for 
their  return.  More  than  ninety-five  per  cent  of 
the  sounding-balloons  liberated  find  their  way 
back  to  the  observatories.  Indeed,  the  zeal 
of  the  finder  is  sometimes  such  that  he  even 
takes  the  trouble  to  polish  the  smoked  cylinder 
on  which  the  records  are  traced. 

Sounding-balloons  reach  astonishing   eleva- 


THE  NEW  SCIENCE  OF  THE  AIR    145 

tions   and  generally  travel   at  railroad  speed. 
Often  they  rise  to  heights  of  over  fifteen  miles 


PROVISIONAL  SELECTION  OF  DATES  FOR  INTERNATIONAL 
AEROLOGICAL  OBSERVATIONS 

(From  "Wiener  Luftschiffer  Zeitung"  Dec.  I,  1909,  with  correc- 
tions subsequently  announced  by  the  International  Commission 
for  Scientific  Aeronautics) 


1910 


1911 


1912 


1913 


January 

February 

March 

April 

May 

June 

July 

August 

September 

October 

November 

December 


6 

2-4 
3 

H 
11-13 

2 

7 
8-13 

i 

6 
2-4 

i 


May  3i-June  2 

6 

3 
4-9 

5 

9 
6-8 


3-S 
i 

7 
11-13 

2 

6 

1-6 
i 

5 
2-4 

7 
5 


6 

4 
5-io 

5 

Is 

4 

2 

5-7 
4 


In  general,  observations  are  made  on  the  first  Thursday 
of  each  month.  Once  a  year  observations  on  an  especially 
extensive  scale  are  made  during  six  successive  days;  this 
is  the  so-called  "International  Week"  and  is  the  occasion 
of  special  aerological  expeditions,  in  which  the  naval  ves- 
sels of  many  countries  participate.  The  month  in  which 
the  International  Week  occurs  varies  from  year  to  year. 
Shorter  series  of  observations,  covering  three  days,  are 
made  during  other  months  —  as  shown  in  this  table. 

The  results  of  the  international  observations  are  col- 
lected and  published  by  the  International  Commission  for 
Scientific  Aeronautics,  which  has  its  headquarters  at  Strass- 
burg. 


and  cover  distances  of  seven  and  eight  hundred 
miles  at  the  rate  of  forty  to  eighty  miles  an 


i46    THE   NEW   ART   OF    FLYING 

hour.  A  paper  balloon  will  reach  its  greatest 
height  in  about  six  hours;  a  rubber  balloon, 
in  three  hours. 

Ascents  with  kites  and  sounding-balloons  are 
regularly  made  on  agreed  dates  by  the  air- 
exploring  stations  of  the  entire  world.  The 
dates  noted  in  the  table  on  page  145  were 
chosen  for  kite  and  balloon  ascents  for  the 
years  1910  to  1913,  inclusive. 

As  a  result  of  many  hundred  flights  made 
by  kites  and  sounding-balloons  by  day  and  by 
night,  in  fair  weather  and  foul,  in  spring  and 
summer,  in  autumn  and  winter,  over  land  and 
sea,  in  the  tropics  and  within  the  arctic  circle, 
we  know  that  even  in  midsummer  we  live  in  a 
comparatively  thin  stratum  of  warm  air.  We 
know,  too,  that  if  we  could  transport  ourselves 
to  a  height  of  ten  miles  and  live  in  the  bitter 
cold,  thin  air  which  would  there  surround  us, 
we  should  find  the  aspect  of  the  heavens  won- 
derfully changed.  The  sky  would  no  longer 
appear  azure  and  suffused  with  light.  By  day  as 
well  as  by  night  it  would  appear  strangely  black. 
Like  brilliant  points  pricked  in  a  sable  canopy, 
the  stars  would  shine  both  at  noon  and  at  mid- 


THE  NEW  SCIENCE  OF  THE  AIR    147 

night.  They  would  shine,  moreover,  not  with 
the  scintillation  to  which  we  are  accustomed  but 
with  relentless  steadiness.  The  sun  would  blaze 


KV. 


FIG.  68.  —  The  extent  of  the  atmosphere  in  a  vertical 
direction.     Heights  in  kilometres. 

so  fiercely  in  that  cloudless  sky  of  jet  that  the 
human  skin  would  blister  under  its  rays.  So 
tenuous  would  be  the  air  that  it  could  not  propa- 


1 48    THE    NEW   ART   OF    FLYING 

gate  sound.  I  could  not  call  to  my  friend  and 
be  heard,  even  though  my  hand  touched  his. 

Much  of  this  might  have  been  guessed  with- 
out the  aid  of  the  elaborate  machinery  that  has 
been  invented  to  explore  the  air.  Much,  how- 
ever, has  been  discovered  that  was  undreamed 
of  in  our  meteorology,  —  among  other  things, 
that  the  air  is  stratified  above  us  in  three  more 
or  less  distinct  layers. 

The  lowermost  of  these  layers,  the  layer  in 
which  we  live  and  which  extends  upward  for 
about  two  miles  from  the  surface  of  the  earth, 
is  a  region  of  turmoil,  warm  to-day  and  cold 
to-morrow.  This  is  the  region  of  whimsical 
winds,  of  cyclones  and  anti-cyclones,  of  cool 
descending  currents  and  warm  ascending  cur- 
rents. All  our  weather  forecasting  is  at  present 
based  upon  what  can  be  learned  from  the  gen- 
eral circulation  of  the  air  in  this  lowermost 
layer,  the  layer  in  which  men  navigate  the  air. 

Beginning  at  the  two-mile  level  that  marks 
the  end  of  the  lowermost  layer  and  extending 
upward  for  a  distance  of  some  five  miles,  we 
find  a  second  stratum  of  air,  —  a  stratum  less 
capricious,  and  one  in  which  the  air  grows 


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THE  NEW  SCIENCE  OF  THE  AIR    149 

steadily  colder  and  drier  with  increasing  height. 
The  lowest  temperature  thus  far  recorded  is 
152°  below  the  Fahrenheit  freezing  point. 
Whatever  thermal  irregularities  there  may  be 
are  caused  by  wide  temperature  changes  on  the 
surface  of  the  earth  and  by  the  reflection  of 
solar  heat  by  the  clouds.  Here  the  air  moves 
in  great  planetary  swirls,  produced  by  the  spin- 
ning of  the  earth  on  its  axis,  so  that  the  wind 
always  blows  in  the  same  eastward  direction. 
The  greater  the  height  the  more  furious  is  the 
blast  of  this  relentless  gale. 

Last  of  all  comes  a  layer  which  was  dis- 
covered by  Teisserenc  de  Bort  and  Dr.  Richard 
Assmann  almost  simultaneously,  and  which  is 
generally  called  the  "  isothermal  stratum  "  be- 
cause the  temperature  varies  but  little  with  alti- 
tude. The  lower  part  of  the  isothermal  layer 
shows  a  slight  increase  in  temperature  with 
increasing  height.  Hence  this  part  of  the  iso- 
thermal layer  is  sometimes  referred  to  as  the 
"  inversion  layer,"  or  region  of  the  upper 
inversion. 

Above  the  inversion  layer  the  vertical  tem- 
perature gradient  is  practically  zero ;  i.  e.,  there 


150    THE    NEW   ART   OF    FLYING 

is  little  or  no  change  of  temperature  with  alti- 
tude. Teisserenc  de  Bort  now  calls  the  isother- 
mal layer  "  stratosphere,"  and  the  use  of  this 
latter  name  is  increasing. 

Although  the  air  is  warmer  than  in  the  layer 
immediately  below,  the  temperature  lies  far 
below  the  Fahrenheit  zero  and  may  be  placed 
somewhere  near  100°  below  the  Fahrenheit 
freezing  point  in  middle  latitudes.  Here  we 
have  a  region  of  meteorological  anomalies 
which  have  not  yet  been  satisfactorily  explained. 
In  passing  from  the  second  to  the  isothermal 
layer,  the  wild  blasts  of  wind  are  stilled  to  a 
breeze,  the  velocity  decreasing  from  twenty- 
five  to  eighty  per  cent.  The  air  no  longer 
whirls  in  a  planetary  circle.  Indeed,  the  wind 
may  blow  in  a  direction  quite  different  from 
that  in  the  second  layer.  Whatever  may  be 
the  moisture  of  the  air  below,  it  is  always  exces- 
sively dry  in  the  permanent  inversion  layer. 
Just  where  this  isothermal  layer  begins  depends 
on  the  season,  the  latitude,  the  barometric  pres- 
sure, and  perhaps  on  other  factors  still  unknown. 
Just  where  it  ends  no  one  knows;  for  although 
sounding  balloons  have  risen  to  heights  of  over 


THE  NEW  SCIENCE  OF  THE  AIR    151 

eighteen  miles,  its  upper  limit  has  not  yet  been 
discovered.  In  summer  time  the  isothermal 
layer  over  middle  latitudes  begins  at  a  height 
of  about  seven  miles  above  the  earth.  We  know 
that  the  higher  it  lies  the  colder  it  is,  that  the 
lower  it  lies  the  warmer  it  is.  We  know,  too, 
that  there  is  no  bodily  shifting  up  and  down  of 
warm  and  cold  masses  of  air  in  that  mysterious 
region.  The  result  is  that  a  current  ascending 
from  the  lower  level  spreads  out  when  it  en- 
counters the  "  permanent-inversion  "  layer  as  if 
a  solid  barrier  had  been  interposed. 

Up  to  the  height  of  the  "  permanent-inver- 
sion "  layer  the  temperature  falls  at  a  rate 
which  increases  somewhat  with  altitude,  but 
which  may  be  placed  roughly  at  rather  over 
y2°  C.  per  hundred  metres  (say  i°  F.  per  three 
hundred  to  four  hundred  feet),  so  that  on  a 
hot  summer's  day  with  a  temperature  of  90° 
Fahrenheit  at  the  earth's  surface,  a  man  could 
place  himself  in  fairly  cool  surroundings  if  he 
could  rise  only  fifteen  hundred  feet.  Because 
of  the  constant  upheavals  to  which  the  air  is 
subject  in  its  lower  levels,  this  average  rate  of 
temperature  reduction,  as  we  ascend,  is  not 


iS2    THE    NEW   ART   OF    FLYING 

often  observed.  It  may  even  happen  that  for 
a  short  distance  the  thermometer  may  rise 
and  not  fall  at  all.  Ultimately,  the  tempera- 
ture drops  at  a  uniform  rate  until  it  reaches  a 
point  lower  than  that  reported  by  any  North- 
pole  explorer. 

To  these  fluctuating  temperatures  in  the 
lowermost  layer  clouds  and  rain  are  due.  Warm 
air  tends  to  rise  and  to  cool  as  it  rises.  The 
cooling  air  in  turn  condenses  its  water  vapor 
into  clouds.  This  process,  as  well  as  others  that 
need  not  be  considered  here,  leads  ultimately 
to  the  precipitation  of  the  condensed  water  of 
atmosphere,  as  rain,  snow,  or  hail. 

The  three  layers  of  air  which  have  been  dis- 
closed to  us  by  the  sensitive  instruments  of 
modern  meteorology  intermingle  but  slightly. 
The  one  floats  upon  the  other  as  oil  floats  upon 
water.  Of  the  great  ocean  of  air  at  the  bottom 
of  which  we  move  and  live,  three  fourths  by 
mass  lie  below  the  isothermal  layer.  All  our 
storms,  our  clouds,  and  all  dust,  except  such  as 
may  be  of  volcanic  or  cosmical  origin,  are  phe- 
nomena of  the  lower  two  layers. 

When  the  meteorologist  has  fully  discovered 


Photograph  by  Edwin  Levick 

Fig.  47. — The  motor  and  the  propeller  of  a  R.  E.  P. 

(Robert  Esnault-Pelterie)    monoplane.     Robert 

Esnalt-Pelterie    has    abandoned    this    four- 

bladed   metal   propeller   for  the  more 

efficient  two-bladed  wooden  propeller 


THE  NEW  SCIENCE  OF  THE  AIR    153 

the  influence  which  the  upper  region  exerts  upon 
the  lower,  there  is  reason  to  hope  that  he  will 
be  able  to  foretell  the  weather  not  merely  a 
day  but  perhaps  a  week  or  more  in  advance, 
and  to  prepare  charts  which  will  be  as  useful  to 
the  aviator  as  the  charts  which  warn  the  mariner 
of  shoals  and  reefs. 

The  currents  in  the  various  levels  of  the 
atmosphere  are  of  as  much  importance  to  the 
aviator  as  are  the  ocean  currents  to  the  mariner. 
Hence  the  necessity  of  charting  the  sea  of  air 
with  scientific  care,  and  hence  the  value  of  the 
work  here  outlined.  The  International  Commis- 
sion for  Scientific  Aeronautics  has  already  accu- 
mulated sufficient  data  to  chart  aerial  routes, 
comparable  with  the  ocean  routes  laid  down 
by  the  various  hydrographic  officers  of  the 
world.  Every  government  will  have  a  special 
branch  of  research  and  will  distribute  infor- 
mation for  aeronauts.  The  daily  weather 
reports  will  be  amplified  to  suit  the  flying  man. 

Thus  far  more  interest  has  been  shown  in 
Europe  than  in  this  country  in  this  matter  of 
vital  importance  to  the  aeronaut.  A  detailed 
analysis  of  the  wind  data  available  for  the 


154    THE    NEW   ART   OF    FLYING 

German  Empire  was  undertaken  by  Dr.  Richard 
Assmann  at  the  instance  of  the  "  Motorluftschiff- 
Studiengesellschaft,"  founded  by  the  Kaiser. 
That  society,  whose  name  translated  into  Eng- 
lish reads  u  Society  for  the  Study  of  Motor 
Airships,"  recently  published  the  results  of  Ass- 
mann. The  Italian  Aeronautical  Society  has 
performed  a  similar  service  for  Italy.  Such 
data  will  be  useful  to  the  aeronaut  in  selecting 
sites  for  practising  grounds  or  for  aerial  har- 
bours, or  in  choosing  the  seasons  most  appro- 
priate for  experiment. 

Dr.  Richard  Assmann,  director  of  the  Royal 
Prussian  Aeronautical  Observatory  of  Linden- 
berg,  in  an  article  entitled  "  The  Dangers  of 
Aerial  Navigation  and  the  Means  of  Diminish- 
ing Them,"  contributed  to  the  Deutsche  Zeit- 
schrift  fur  Luftschifahrt,  describes  the  aeronau- 
tical weather  service  that  he  is  organising,  and 
of  which  Lindenberg  Observatory  is  to  be  the 
centre.  According  to  Dr.  Assmann  at  least 
three  similar  tentative  schemes  have  already 
been  put  into  execution  in  the  German  Empire. 
The  first  was  undertaken  by  the  Lindenberg 
Observatory  in  1907,  during  trial  trips  made 


THE  NEW  SCIENCE  OF  THE  AIR    155 

by  the  "  Parseval  "  airship.  Observations  of 
the  upper  air  currents  were  made  simultaneously 
at  five  stations  by  means  of  pilot  balloons  and 
communicated  to  the  crew  of  the  airship,  who 
were  thus  materially  aided  in  guiding  their 
craft.  The  second  similar  undertaking  was 
Dr.  Linke's  special  weather  service  for  aero- 
nauts, conducted  at  the  Frankfort  Aeronautical 
Exposition  of  1910.  The  third  aeronautical 
service  was  organised  by  Dr.  Polis,  at  Aachen. 
It  is  still  in  existence,  and  is  intended  especially 
for  the  benefit  of  the  aero  clubs  of  the  Rhein- 
land.  Its  usefulness  was  demonstrated  during 
the  army  manoeuvres  in  West  Prussia  in  1910. 

Next  to  the  United  States,  Germany  has 
probably  the  best  organised  weather  service  in 
the  world.  It  is  therefore  not  astonishing  that 
Germany  should  be  better  prepared  than  any 
other  European  state  for  the  adaptation  of 
modern  meteorological  science  to  the  needs  of 
the  airman.  Lindenberg  Observatory  is  now 
equipping  the  Public  Weather  Service  stations 
with  the  apparatus  needed  for  daily  observa- 
tions of  the  upper  air,  not  primarily  for  the 
purpose  of  improving  the  weather  forecasts, 


1 56    THE    NEW    ART    OF    FLYING 

but  in  order  to  lessen  the  dangers  of  aerial 
navigation,  —  dangers,  in  Assmann's  opinion, 
largely  avoidable  and  to  which  the  loss  of 
twenty  valuable  lives  in  Germany  during  1910 
may  be  attributed.  At  the  present  time  the 
navigator  of  the  air  launches  his  craft  with 
no  more  knowledge  of  the  meteorological  con- 
ditions in  the  upper  air  than  can  be  surmised 
from  those  depicted  in  the  ground-service 
weather  map.  The  day  is  not  far  distant  when 
he  will  have  a  weather  map  all  his  own. 

In  Dr.  Assmann's  plan,  a  number  of  the 
Public  Weather  Service  stations  are  to  be  fur- 
nished by  the  Lindenberg  Observatory  with  a 
theodolite,  an  inflating-balance  for  determining 
the  ascensional  force  of  the  balloons,  a  sufficient 
number  of  balloons,  and  the  necessary  graphic 
tables  for  rapidly  working  up  the  observations. 

At  8  A.  M.  every  day,  assuming  the  weather 
is  favourable,  the  stations  will  be  expected  to 
send  up  a  pilot  balloon  and  to  trace  its  course 
with  the  theodolite  as  long  as  possible.  The 
observation  will  then  be  worked  up  —  a  matter 
of  barely  a  quarter  of  an  hour  for  a  practised 
observer  —  and  telegraphed  to  Lindenberg. 


Photograph  by  Edwin  Levick 

Fig.  48. — Henry  Farman  seated  in  his  biplane  with 
three  passengers 


THE  NEW  SCIENCE  OF  THE  AIR    157 

Here  the  observations  received  from  all  other 
stations  will  be  assembled  and  re-distributed  in 
a  single  telegram  sent  to  each  of  the  cooperat- 
ing stations.  If  they  arrive  in  time,  the  tele- 
grams can  be  utilised  in  connection  with  the 
ordinary  daily  weather  forecast,  as  well  as  for 
the  preparation  of  special  forecasts  and  warn- 
ings for  airmen.  At  Lindenberg  the  regular 
observation  with  a  kite  or  capture  balloon  is 
made  daily  at  8  A.  M.,  and  in  summer  an  ob- 
servation is  also  made  about  5  or  6  A.  M. 
Assmann  also  proposes  to  conduct  daily  ob- 
servations at  Lindenberg  with  a  pilot  balloon 
at  ii  A.  M.,  and,  whenever  necessary,  another 
about  2  p.  M.,  so  that  soundings  of  the  air  to 
an  altitude  of  several  miles  will  be  made  three 
or  four  times  a  day  within  a  period  of  six  to 
nine  hours.  Thus  valuable  information  will  be 
gathered  which  ought  to  enable  the  weather 
forecaster  to  warn  airmen  of  impending  changes 
in  the  lower  atmosphere,  on  the  basis  of  act- 
ually occurring  rapid  changes  in  the  upper 
atmosphere. 

That  the  German   Public  Weather   Service 
stations  will  ultimately  be  supplemented  with 


158    THE    NEW   ART   OF    FLYING 

stations  especially  erected  for  the  purpose  at 
the  larger  aviation  fields  and  the  like,  would 
seem  to  follow  from  the  work  now  done 
at  the  experimental  observatory  at  Bitterfeld, 
from  the  erection  of  the  aeronautical  observa- 
tory on  the  Inselberg,  near  Gotha,  from  the 
probability  of  the  erection  of  the  long-promised 
aerological  station  at  Taunus,  and  lastly,  from 
the  contemplated  installation  of  aerological 
stations  at  nautical  schools  on  the  coast. 

The  difficulty  of  following  pilot  ballqons  in 
hazy  weather  and  at  dusk  leads  Assmann  to 
propose  the  utilisation  of  balloons  of  two  sizes, 
the  smaller  and  cheaper  to  be  used  when  it  is 
evident  that  the  state  of  the  sky  will  not  per- 
mit the  balloon  to  be  followed  with  the  the- 
odolite to  a  great  distance.  Observations  at 
night  could  be  made  by  illuminated  balloons, 
but  at  considerable  expense. 

Undoubtedly  there  will  be  many  days  on 
which  few,  if  any,  observations  can  be  secured 
with  pilot  balloons,  so  that  only  the  observa- 
tions made  at  stations  equipped  with  captive 
balloons  and  kites  will  be  available.  In  order 
to  meet  this  serious  difficulty,  Assmann  is  con- 


THE  NEW  SCIENCE  OF  THE  AIR    159 

sidering  the  plan  of  supplying  a  few  selected 
stations  with  a  central  and  easily  manageable 
kite  outfit. 

Thus  far  the  plan  outlined  by  Dr.  Assmann 
has  been  approved  only  for  a  limited  part  of 
the  Empire.  Political  heterogeneity  still  ham- 
pers imperial  undertakings  in  Germany.  Ulti- 
mately, however,  the  field  of  observations 
will  be  extended  to  include  the  south  German 
states,  where  some  very  important  stations  are 
located,  chief  among  which  is  the  admirably 
equipped  station  at  Friedrichshafen  on  Lake 
Constance. 

Assmann  himself  realises  that  his  plan  can- 
not hope  to  provide  detailed  information  and 
forecasts  of  local  conditions  except  in  so  far 
as  may  be  inferred  from  the  general  outlook. 
Some  experiments  which  were  recently  made 
in  Germany,  after  the  appearance  of  Dr.  Ass- 
mann's  article,  show  that  it  is  feasible  to  secure 
a  corps  of  special  thunderstorm  observers  who 
can  report  by  telegraph  and  telephone,  and  who 
are  numerous  enough  to  enable  the  weather 
forecaster  to  follow  the  progress  of  sudden 
atmospheric  disturbances  across  the  country, 


i6o    THE    NEW   ART   OF    FLYING 

and  to  give  timely  warning  to  the  aeronaut  to 
avoid  them. 

Apart  from  enlightening  the  aeronaut  on  the 
condition  of  the  atmosphere,  it  will  be  obviously 
necessary  to  provide  the  equivalent  of  automo- 
bile road  maps,  —  something  that  will  tell  the 
man  of  the  air  where  he  is.  It  is  very  difficult 
to  recognise  even  familiar  country  from  above. 
During  his  flight  down  the  Hudson  River,  Cur- 
tiss  decided  to  alight  on  what  looked  to  him 
like  a  fine  green  field.  Swooping  down,  he 
found  that  his  green  field  was  a  terrace,  an  un- 
avoidable error  in  judgment  which  might  have 
cut  short  his  triumphal  flight.  With  a  map  on  a 
scale  of  half  an  inch  to  the  mile,  showing  the 
lines  of  the  roads  and  the  shapes  of  the  villages, 
it  would  seem  easy  enough  to  ascertain  one's 
whereabouts;  but  the  aviator  travels  quickly 
and  a  full  equipment  of  half-inch  maps  would 
be  a  serious  item  in  the  weight  of  his  load. 
The  man  in  a  balloon  is  often  above  clouds, 
and  when  he  views  the  earth  again  it  is  very 
difficult  and  frequently  impossible  to  pick  up 
the  route  again.  The  aviator  in  a  flying-ma- 
chine is  more  favourably  placed.  He  knows  his 


Fig.  63. — Motor  of  the  Wright  biplane 


THE  NEW  SCIENCE  OF  THE  AIR    161 

direction  approximately,  although  he  is  often 
unable  to  make  proper  allowance  for  the  drift- 
ing effect  of  the  wind.  If  caught  by  varying 
currents  or  by  storms  above  the  clouds,  he  easily 
loses  track  of  the  course.  There  will  be  need 
of  large  distinctive  ground  marks  for  day  and 
lights  for  night  at  distances  of  ten  miles  apart, 
marks  which  will  correspond  with  those  on  an 
air-chart.  Zeppelin  proposes  maps  showing 
heights  by  colours,  and  marks  indicating  the 
influence  of  streams,  marshes,  and  woods  on 
the  static  equilibrium  of  the  airship.  The  scale 
he  suggests  is  three  miles  to  the  inch.  Colour 
is  the  main  consideration.  In  the  opinion  of 
Mr.  Charles  Cyril  Turner,  an  English  aero- 
naut, the  colours  should  approximate  to  the 
colours  of  the  landscape  as  seen  from  above. 
The  roads  should  be  white,  the  water  blue,  the 
fields  light  green,  woods  a  darker  green,  habi- 
tations grey,  and  railways  black. 

Besides  guiding  the  aerial  traveller  on  his 
way  some  means  must  be  devised  of  conveying 
useful  information  to  him.  It  will  often  be  of 
great  importance  to  know  the  strength  and  exact 
direction  of  the  wind.  Skimming  the  air  at  the 


1 62    THE    NEW   ART   OF    FLYING 

rate  of  fifty  miles  an  hour,  the  aviator  will  find 
it  difficult  if  not  impossible  to  make  these  obser- 
vations. The  German  Aerial  Navy  League  has 
suggested  that  special  light-houses  be  con- 
structed for  that  purpose.  These  are  to  send 
a  long  beam  of  light  in  the  direction  in  which 
the  wind  is  blowing.  For  day  flights  it  will 
probably  be  necessary  to  have  a  long  arrow 
painted  white  and  swinging  on  a  pivot  so  that 
it  can  be  turned  in  the  proper  direction. 


CHAPTER   X 

THE  PERILS  OF  FLYING 

FROM  what  has  been  said  in  the  foregoing 
chapter  it  may  well  be  inferred  that  a  man  who 
attempts  to  fly  in  the  unsteady  lower  stratum 
of  the  atmosphere  in  which  we  live  is  almost 
in  the  same  position  as  a  drop  of  quicksilver  on 
an  exceedingly  unsteady  glass  plate.  Unlike  the 
drop  of  quicksilver,  however,  he  is  provided 
with  a  more  or  less  imperfect  apparatus  for 
maintaining  a  given  course  on  the  unsteady 
medium  to  which  he  trusts  himself. 

Were  it  not  that  the  whirling  maelstroms, 
the  quiet  pools,  the  billows  and  breakers  of  the 
great  sea  of  air  are  invisible,  the  risks  of  flying 
would  perhaps  not  be  so  great.  Only  the  man 
in  the  air  knows  how  turbulent  is  the  atmosphere 
even  at  its  calmest.  "  The  wind  as  a  whole," 
wrote  Langley  a  decade  ago,  "  is  not  a  thing 
moving  along  all  of  a  piece,  like  the  water  in 
the  Gulf  Stream.  Far  from  it.  The  wind, 
when  we  come  to  study  it,  as  we  have  to  do 


1 64    THE    NEW   ART   OF    FLYING 

here,  is  found  to  be  made  of  innumerable  cur- 
rents and  counter-currents  which  exist  altogether 
and  simultaneously  in  the  gentlest  breeze,  which 
is  in  reality  going  fifty  ways  at  once,  although, 
as  a  whole,  it  may  come  from  the  east  or  the 
west;  and  if  we  could  see  it,  it  would  be  some- 
thing like  seeing  the  rapids  below  Niagara, 
where  there  is  an  infinite  variety  of  motion  in 
the  parts,  although  there  is  a  common  move- 
ment of  the  stream  as  a  whole." 

Through  these  invisible  perils  the  airman 
must  feel  his  way  in  the  brightest  sunshine,  like 
a  blind  man  groping  his  way  in  a  strange  room. 
He  can  tell  you  that  against  every  cliff,  every 
mountain  side,  every  hedge,  every  stone  wall, 
the  air  is  dashed  up  in  more  or  less  tumultuous 
waves.  The  men  who  crossed  the  English 
Channel  found  that  against  the  chalk  cliffs  of 
Dover  a  vast,  invisible  surf  of  air  beats  as  furi- 
ously as  the  roaring,  visible  surf  in  the  Channel 
below, —  a  surf  of  air  that  drove  nearly  all  of 
them  out  of  their  course  and  imperilled  their 
lives.  There  are  whirlpools,  too,  near  those 
cliffs  of  Dover,  as  Moisant  used  to  tell.  He 
was  sucked  down  into  one  of  them  within  two 


THE    PERILS    OF    FLYING       165 

hundred  feet  of  the  sea.  His  machine  lurched 
heavily,  and  it  was  with  some  difficulty  that 
he  managed  to  reascend  to  a  height  at 
which  he  could  finish  the  crossing  of  the 
Channel. 

Sometimes  there  are  descending  currents  of 
air  with  very  little  horizontal  motion,  just  as 
dangerous  as  the  breakers.  Into  such  mael- 
stroms the  pilot  may  drop  as  into  unseen  quick- 
sands. On  his  historic  flight  down  the  Hudson 
River,  Curtiss  ran  into  such  a  pitfall,  fell  with 
vertiginous  rapidity,  and  saved  himself  only  by 
skilful  handling  of  his  biplane.  A  less  experi- 
enced pilot  would  have  dropped  into  the  river. 
A  sudden  strong  gust  blowing  with  the  machine 
would  have  a  similar  effect. 

Such  are  the  concentration  of  mind  and  the 
dexterity  required  by  very  long  cross-country 
flights  that  a  man's  strength  is  often  sapped. 
During  the  Circuit  de  I'Est  of  1910,  in  which 
the  contestants  were  compelled  to  fly  regardless 
of  the  weather,  the  German,  Lindpaintner,  had 
to  give  up  because  of  physical  and  nervous  ex- 
haustion. Another  competitor  crawled  under 
his  machine,  as  soon  as  he  alighted,  and  went 


1 66    THE    NEW   ART    OF    FLYING 

asleep.  Wilbur  Wright  has  been  credited  with 
the  remark:  "  The  more  you  know  about  the 
air,  the  fewer  are  the  chances  you  are  willing  to 
take.  It 's  your  ignorant  man  who  is  most 
reckless." 

Because  of  the  air's  trickiness,  starting  and 
alighting  are  particularly  difficult  and  dangerous. 
More  aeroplanes  are  wrecked  by  novices  in  the 
effort  to  rise  than  from  any  other  cause.  As  a 
general  rule  a  new  man  tilts  his  elevating  rudder 
too  high,  and  because  he  has  not  power  enough 
to  ascend  at  a  very  steep  angle,  he  slides  back 
with  a  crash.  In  high  winds  even  practised 
airmen  find  it  hard  to  start.  During  the  meeting 
at  Havre  in  August,  1910,  Leblanc  and  Morane 
were  invited  to  luncheon  at  Trouville.  Like 
true  pilots  of  the  air  they  decided  to  keep  their 
engagements  by  travelling  in  their  machines. 
At  half  past  eleven  they  ordered  their  Bleriots 
trundled  from  their  sheds.  Twice  they  were 
dashed  back  by  the  wind  before  they  succeeded 
in  taking  the  air.  An  untried  man  would  have 
wrecked  his  machine  in  that  wind. 

The  pneumatic  tired  wheels  on  which  a  ma- 
chine runs  in  getting  up  preliminary  speed  serve 


Photograph  by  Edwin  Levick 

Fig.  64. — Two-cylinder  Anzani  motor  on  a  Letourd- 
Niepce  monoplane 


THE    PERILS   OF    FLYING       167 

also  for  alighting,  as  we  have  seen.  When  a 
monoplane  glides  down  at  the  rate  of  forty- 
five  miles  an  hour  and  strikes  the  ground,  some 
disposition  must  be  made  of  its  energy.  Usu- 
ally skids  or  runners,  like  those  of  a  sled,  are 
employed  for  that  purpose,  the  bicycle  wheels 
giving  way  under  the  action  of  springs,  so  as 
to  permit  the  skids  to  arrest  the  machine.  Men 
like  the  Wrights  can  bring  an  aeroplane  to  a 
stop  without  spilling  a  glass  of  water;  but  your 
unpractised  hand  often  comes  down  with  a 
shock  that  makes  splinters  of  a  high-priced 
biplane. 

Inexperience  in  the  correct  manipulation  of 
stabilising  devices  is  a  fruitful  cause  of  acci- 
dents, —  perhaps  the  most  fruitful.  The  ma- 
nipulation of  these  corrective  devices  is  no  easy 
art.  Machines  and  necks  have  been  broken  in 
the  effort  to  acquire  it.  Man  and  aeroplane 
must  become  one.  The  horizontal  rudder, 
which  projects  forward  from  many  biplanes,  is 
like  the  cane  of  a  blind  man.  With  it  the  pilot 
feels  his  way  up  or  down,  yet  without  touching 
anything.  -Balancing  from  side  to  side  is  even 
more  difficult.  Curiously  enough,  it  is  when  the 


1 68    THE    NEW    ART    OF    FLYING 

machine  is  near  the  ground  that  it  is  hardest 
of  all  to  bring  the  aeroplane  back  to  an  even 
keel.  Imagine  yourself  for  the  first  time  in  your 
life  seated  in  a  biplane  with  a  forty-foot  span 
of  wing,  sailing  along  at  the  rate  of  thirty-five 
miles  an  hour,  about  ten  feet  from  the  ground. 
If  your  machine  suddenly  drops  on  one  side,  it 
will  scrape  on  the  ground  before  you  can  twist 
your  planes  and  lift  the  falling  side  by  increasing 
the  air  pressure  beneath  it.  You  will  come 
down  with  a  crash.  If,  on  the  other  hand,  you 
are  an  old  air-dog,  you  will  tilt  up  your  hori- 
zontal or  elevation  rudder  and  glide  up  before 
you  attempt  to  right  yourself.  So,  too,  if  you 
see  a  stone  wall  or  a  hedge  in  your  course,  you 
will  lift  yourself  high  above  it.  Why?  To 
avoid  the  waves  of  air  dashed  up  against  the 
wall  or  hedge.  For  if  you  did  not  rise,  the 
waves  would  catch  you  and  toss  you  about,  and 
you  might  lose  your  aerial  balance. 

In  this  connection  Prof.  G.  H.  Bryan  has 
pointed  out  that  the  distinction  between  equi- 
librium and  stability  should  be  kept  in  mind. 
An  aeroplane  is  in  equilibrium  when  travel- 
ling at  a  uniform  rate  in  a  straight  line,  or, 


THE   PERILS   OF   FLYING      169 

again,  when  being  steered  round  a  horizontal 
arc  of  a  circle.  A  badly  balanced  aeroplane 
would  not  be  able  to  travel  in  a  straight  line. 
The  mathematics  of  aeroplane  equilibrium  are 
probably  very  imperfectly  understood  by  many 
interested  in  aviation,  but  they  are  compara- 
tively simple,  while  the  theory  of  stability  is 
of  necessity  much  more  difficult. 

It  is  necessary  for  stability  that  if  the  aero- 
plane is  not  in  equilibrium  and  moving  uniformly 
it  shall  tend  toward  a  condition  of  equilibrium. 
At  the  same  time  it  may  commence  to  oscillate, 
describing  an  undulating  path,  and  if  the  oscil- 
lations increase  in  amplitude  the  motion  will  be 
unstable.  It  is  necessary  for  stability  that  an 
oscillatory  motion  shall  have  a  positive  modulus 
of  decay  or  coefficient  of  subsidence,  and  the 
calculation  of  this  is  an  important  feature  of 
the  investigation. 

At  the  present  time  it  is  certain  that  aviators 
rely  entirely  on  their  own  exertions  for  control- 
ling machines  that  'are  unstable,  or  at  least 
deficient  in  stability,  and  they  go  so  far  as  to 
declare  that,  owing  to  the  danger  of  sudden 
gusts  of  wind,  automatic  stability  is  of  little 


1 70    THE    NEW   ART    OF    FLYING 

importance.  Moreover,  even  in  the  early  exper- 
iments of  Pilcher,  it  was  found  that  a  glider 
with  too  V-shaped  wings,  or  with  the  centre  of 
gravity  too  low  down,  is  apt  to  pitch  danger- 
ously in  the  same  way  that  increasing  the  meta- 
centric  height  of  a  ship  while  increasing  its 
"  statical "  stability  causes  it  to  pitch  danger- 
ously. It  thus  becomes  important  to  consider 
what  is  the  effect  of  a  sudden  change  of  wind 
velocity  on  an  aeroplane.  If  the  aeroplane  was 
previously  in  equilibrium,  it  will  cease  to  be  so, 
but  will  tend  to  assume  a  motion  which  will 
bring  it  into  the  new  state  of  equilibrium  con- 
sistently with  the  altered  circumstances,  provided 
that  this  new  motion  is  stable.  Thus  an  aero- 
plane of  which  every  steady  motion  is  stable 
within  given  limits  will  constantly  tend  to  right 
itself  if  those  limits  are  not  exceeded.  Exces- 
sive pitching  or  rolling  results  from  •  a  short 
period  of  oscillation  combined  with  a  modulus 
of  decay  which  is  either  negative  (giving  insta- 
bility) or  of  insufficient  magnitude  to  produce 
the  necessary  damping. 

More  difficult  than  the  maintenance  of  sta- 
bility is  the  making  of  a  turn.    The  dangers  that 


THE    PERILS   OF    FLYING       171 

await  the  unskilled  aviator  who  first  tries  to 
sweep  a  circle  have  been  sufficiently  dwelt  upon 
in  Chapter  VI.  The  canting  of  a  machine  at 
a  considerable  angle,  which  is  necessary  in  order 
that  the  weight  of  the  machine  may  be  op- 
posed to  the  centrifugal  force  generated  in 
turning,  necessarily  implies  that  the  aeroplane 
shall  be  at  a  height  great  enough  to  clear  the 
ground.  Yet  many  of  the  early  experimenters 
wrecked  their  apparatus  because  they  tried  to 
make  turns  when  too  near  the  ground,  with  , 
the  result  that  one  wing  would  strike  the  turf 
and  crumple  up  like  paper. 

Even  at  great  heights  the  making  of  a  turn 
is  not  unattended  with  danger,  particularly  when 
the  machine  is  brought  around  suddenly.  If  a 
turn  is  made  too  abruptly,  parts  of  the  structure 
are  sometimes  strained  to  the  breaking-point. 
There  is  good  reason  to  believe  that  the  Hon. 
C.  S.  Rolls  was  killed  because  he  made  too 
quick  a  turn. 

Flying  exhibitions,  which  tempt  the  prize- 
winning  airmen  to  be  overbold,  are  responsible 
for  many  of  the  tragedies  that  have  occurred 
within  the  last  few  years.  At  the  Reims  meeting 


172    THE    NEW   ART   OF    FLYING 

of  1910,  as  many  as  eighteen  machines  were 
circling  around  one  another,  swooping  down, 
hawklike,  from  great  heights,  or  cutting  figure- 
of-eight  curves  to  the  plaudits  of  an  enthusi- 
astic multitude.  It  was  not  the  possibility  of 
collision  that  was  so  perilous,  but  the  disturb- 
ance created  in  the  air.  The  wake  that  every 
steamer  leaves  behind  it  has  its  counterpart  in 
the  wake  that  trails  behind  an  aeroplane  in  the 
air.  A  rowboat  may  ride  safely  through  the 
steamer's  wake  with  much  bobbing;  an  aero- 
plane caught  in  the  wake  of  another  pitches 
alarmingly.  That  was  how  the  Baroness  de  la 
Roche  met  with  such  a  terrible  accident  at  the 
Reims  meeting  in  question. 

The  various  accidents  which  have  occurred 
recently  to  aeroplanes  raise  the  whole  question 
of  whether  the  construction  of  the  wings  is  such 
as  to  give  the  requisite  margin  of  safety  to 
insure  their  not  breaking  under  the  loads  which 
are  likely  to  be  thrown  upon  them  in  use.  In 
all  ordinary  construction,  as  in  building  a  steam- 
boat or  a  house,  engineers  have  what  they  call 
a  factor  of  safety.  An  iron  column,  for  instance, 
will  be  made  strong  enough  to  hold  five  or  ten 


THE    PERILS   OF    FLYING       173 

times  the  weight  that  is  ever  going  to  be  put 
upon  it,  but  if  we  try  anything  of  the  kind  in 
flying-machines  the  resultant  structure  will  be 
too  heavy  to  fly.  Everything  in  the  work  must 
be  so  light  as  to  be  on  the  edge  of  disaster. 
Some  of  the  worst  accidents  on  record  are  to 
be  attributed  to  this  necessarily  flimsy  construc- 
tion. It  is,  of  course,  very  difficult  in  the  case 
of  aeroplane  accidents  to  ascertain  which  part 
broke  first,  for  the  fabric  is  generally  so  utterly 
destroyed  that  no  details  of  the  first  breakage 
can  be  seen.  Further,  the  aviator,  who  is  the 
only  man  who  can  tell  accurately  what  happened, 
is  frequently  killed,  so  that  the  only  information 
available  is  what  can  be  seen  of  the  fall  while 
the  machine  is  in  the  air,  and  accidents  occur 
so  suddenly  that  different  people  do  not  always 
get  the  same  impression  of  the  sequence  of 
events.  There  seems,  however,  little  doubt  that 
in  several  cases  the  wings  collapsed  in  some  way 
while  the  machine  was  flying,  and  that  it  fell 
in  consequence. 

In  the  case  of  a  biplane  (Fig.  69)  the  framing 
of  the  main  wings  usually  consists  of  four  longi- 
tudinals running  the  whole  span  of  the  wings, 


i74    THE    NEW   ART   OF    FLYING 

and  these  are  braced  together,  both  vertically 
and  horizontally,  with  numerous  cross-struts 
and  wire  diagonals,  so  as  to  give  them  very 
great  strength,  both  vertically  and  horizontally. 
In  fact,  if  the  stresses  of  the  diagonal  wires  be 
worked  out,  they  are  found  to  be  very  much 
below  those  usual  in  ordinary  engineering  work. 
Still,  the  wires  are  so  numerous  that,  even  if  one 
of  them  breaks  from  vibration,  the  extra  stress 
thrown  on  the  adjacent  ones  will  not  bring  the 
load  up  to  the  ordinary  stresses  allowed  in 
girder  work.  The  horizontal  strength  is  also 
practically  equal  to  the  vertical,  as  the  trussing 
is  generally  of  the  same  character. 

In  the  monoplane  the  trussing  is  much 
simpler.  Often  there  is  no  horizontal  trussing 
at  all.  The  vertical  strength  of  the  main  plane 
is  entirely  dependent  on  stays,  generally  four  to 
each  side,  which  go  to  the  bottom  of  a  strut 
under  the  backbone.  Should  one  of  these  break, 
the  probability  is  that  the  wing  will  collapse 
with  disastrous  results.  These  stays  are  often 
single  parts  of  steel  wire  or  ribbon,  a  material 
which  has  not  been  found  sufficiently  reliable 
for  use  as  supports  to  the  masts  of  small  sailing 


Photograph  by  George  Brayton 

Fig.  66. — Sending  up  the  first  of  a  pair  of  tandem 
kites  at  the  Blue  Hill  Observatory 


THE    PERILS   OF    FLYING       175 

boats,  where  wire  rope  is  always  preferred,  on 
account  of  the  warning  it  gives  before  breakage. 

The  structure  of  each  wing  in  a  monoplane 
is,  in  fact,  very  much  like  that  of  the  mast  and 
rigging  of  a  sailing  boat,  the  main  spars  taking 
the  place  of  the  mast,  while  the  wire  stays  take 
that  of  the  shrouds.  A  very  important  differ- 
ence, however,  is  that  the  mast  of  a  sailing 
boat  is  almost  invariably  provided  with  a  fore- 
stay  to  take  the  longitudinal  pressure  when 
going  head  to  wind,  while  the  wing  of  an  ae'ro- 
r :  me,  as  we  have  already  noted,  often  has  no 
such  provision,  the  longitudinal  pressure  due 
to  the  air  resistance  being  taken  entirely  by  the 
spar. 

When  a  monoplane  is  flitting  through  the 
air  at  the  rate  of  sixty  miles  an  hour,  the  wire 
stays  often  vibrate  so  fast  that  they  emit  a 
distinct  musical  note.  The  small  boy  who  wants 
to  break  a  piece  of  wire  simply  bends  it  back  and 
forth  many  times  at  a  given  point.  Rapid 
vibration  of  wires  and  ribbons  on  monoplanes 
will  ultimately  produce  the  same  result.  For 
safety's  sake  either  wire  rope  should  be  used 
(heavier  and  therefore  undesirable  from  the 


176    THE    NEW   ART   OF    FLYING 

record-breaker's  standpoint),  or  the  number  of 
stays  must  be  increased  so  that  the  parting  of 
one  will  not  necessarily  spell  a  wreck  and  pos- 
sibly death. 

The  horizontal  stresses  thrown  on  the  single 
supporting  surface  of  an  aeroplane  are  greater 
than  most  pilots  realise.  In  one  of  those  breath- 
less downward  swoops  which  almost  bring  your 
heart  to  your  throat,  or  in  one  of  those  quick 
turns  in  which  the  machine  seems  to  stand  on 
end,  the  stresses  are  enormously  increased.  It 
was  the  breaking  of  a  wing  by  overstrain  that 
killed  Delagrange  at  Pau  on  January  4,  1910; 
it  was  overstrain  that  killed  Wachter  at  Reims 
on  July  i,  1910;  it  was  overstrain,  due  to  sharp 
turning,  that  killed  Rolls  on  July  12,  1910,  at 
Bournemouth,  England;  and  it  was  probably 
overstrain  that  weakened  the  wings  of  Chavez's 
monoplane  in  its  battle  with  the  Alpine  winds 
and  resulted  in  the  fatal  accident  that  occasioned 
the  intrepid  Peruvian's  death  on  September  27, 
1910. 

In  commenting  upon  the  lack  of  horizontal 
strength  in  monoplanes,  a  writer  in  Engineering 
observe? ; 


THE    PERILS   OF    FLYING       177 

"  It  is,  no  doubt,  assumed  that  the  weight 
of  the  machine  rests  on  the  wings,  and  that 
this  is  the  main  stress  to  be  provided  for.  This 
is  no  doubt  true,  but  a  careful  consideration  of 
the  horizontal  stresses  will  show  that  these  are 
much  greater  than  might  at  first  sight  appear. 
When  flying  horizontally  the  horizontal  stress 
cannot,  of  course,  exceed  the  thrust  of  the  pro- 
peller, and  must  in  practice  be  considerably  less 
than  this,  as  part  of  that  thrust  is  spent  in  over- 
coming the  resistance  of  the  body  of  the  ma- 
chine, the  tail,  etc.  The  ratio  of  lifting  power 
to  horizontal  stress  will  vary  considerably  in 
different  machines  with  the  efficiency  of  the 
planes,  but  even  with  the  machine  flying  hori- 
zontally the  horizontal  stress  will  probably  be 
in  the  neighbourhood  of  ten  per  cent  of  the 
vertical. 

"  It  appears,  however,  that  there  are  circum- 
stances in  which  the  horizontal  stress  may  be 
very  much  greater  than  this,  for  it  increases  with 
the  speed  of  the  aeroplane  through  the  air,  and 
this  may  be  very  much  greater  when  descending 
than  when  flying  level.  The  wings  contribute 
the  greater  part  of  the  air  resistance,  and  there- 
fore, if  the  aeroplane  is  descending,  it  will  accel- 
erate till  the  horizontal  stress  on  the  wings 
balances  the  acceleration  due  to  gravity.  Thus, 
if  the  aeroplane  descends  at  a  slope  of  one  in 


178    THE    NEW   ART   OF    FLYING 

five,  the  horizontal  pressure  on  the  planes  may 
be  approximately  twenty  per  cent  of  the  weight 
of  the  machine.  If  the  engine  is  kept  running, 
it  will  be  more  than  this  by  the  amount  of  the 
propeller  thrust.  It  is  quite  clear,  therefore, 
that  circumstances  might  arise  in  which  the  hori- 
zontal stress  would  be  some  twenty-five  per  cent 
of  the  vertical. 

"  Now,  if  we  examine  the  framework  of  many 
of  the  monoplanes,  we  find  that  the  horizontal 
strength  of  the  wings  is  nothing  like  twenty-five 
per  cent  of  the  vertical;  in  fact,  it  is  often  prob- 
ably under  five  per  cent.  The  framework  of 
the  wing  consists  of  two  longitudinals,  and  nu- 
merous cross-battens  carrying  the  fabric.  The 
longitudinals  are  the  only  part  fixed  to  the  back- 
bone, and  therefore  take  practically  the  whole 
stress.  These  longitudinals  are  generally  made 
very  deep  in  proportion  to  their  height,  and  are 
often  channelled  on  the  sides  to  make  them  into 
I-section  girders.  It  is  obvious,  therefore,  that 
their  horizontal  strength  is  very  small  indeed 
compared  with  the  vertical.  True,  the  numer- 
ous cross-battens  stiffen  the  wing  perceptibly, 
but  the  extent  to  which  this  is  the  case  can  hardly 
be  calculated;  and  as  they  are  often  only  about 
24  inch  by  %  incn»  and  fastened  with  very  small 
nails,  they  cannot  be  relied  on  to  any  great 
extent.  It  seems,  therefore,  that  either  the 


U 

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G      cu      ^ 

c^     QJ 

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bJD 


THE    PERILS   OF    FLYING       179 

wings  should  have  diagonal  bracing  or  should 
have  stays  in  front  corresponding  to  those  down 
below." 

That  the  question  of  speed  in  descent  is  a 
matter  for  which  provision  should  be  made  is 
shown  by  the  fatal  death  of  Wachter  at  Reims 
in  1910.  The  speed  in  descending  is  higher 
than  when  flying  level.  In  some  cases  the  hori- 
zontal strength  of  the  wings  appears  to  pro- 
vide a  very  small  margin  for  this  increased 
stress,  and  the  accidents  seem  to  have  happened 
exactly  as  suggested,  for  in  each  case,  when 
rapidly  descending  from  a  height,  the  wing 
collapsed. 

It  may  be  said  that  when  descending  the  en- 
gine ought  to  be  stopped  and  the  descent  made 
at  a  speed  not  exceeding  that  which  can  be 
maintained  on  the  level.  Still,  it  is  hardly  prac- 
ticable to  adhere  to  any  such  principle;  for 
in  alighting  it  is  necessary  to  travel  at  top  speed 
to  clear  the  ground  eddies.  Moreover,  if  the 
aeroplane  is  to  be  of  any  practical  use,  it  must 
be  made  to  stand  any  reasonable  usage  to  which 
it  is  likely  to  be  subjected.  Bicycles  and  motor- 
cars are  often  run  down  hill,  or  before  a  wind, 


i8o    THE    NEW   ART   OF    FLYING 

at  speeds  far  higher  than  can  be  maintained  on 
the  flat,  and  it  is  quite  certain  that  a  machine 
which  is  unsafe  under  these  circumstances  is 
not  fit  for  ordinary  work.  Most  men  run  down 
a  hill  as  fast  as  they  can  without  losing  control 
of  their  cars,  and  aviators  will  doubtless  do  the 
same.  The  machine  must,  therefore,  be  made  to 
stand  the  stresses  set  up  under  these  conditions. 

Very  little  is  known  of  the  air's  power  of 
breaking  aeroplanes  travelling  at  high  speeds. 
Designers  work  from  tables  that  indicate  the 
breaking  strength  of  wire  and  wood  and  the 
percussive  force  of  the  wind  at  different  veloci- 
ties. But  the  actual  buffeting  to  which  a  ma- 
chine is  subjected  in  the  air  is  still  an  engineer- 
ing uncertainty.  A  storm  will  tear  the  roof 
from  a  house  and  toss  it  a  hundred  yards ;  yet 
aeroplane  designers  require  a  machine  to  travel 
through  the  air  at  hurricane  speed  and  bear  up 
under  the  sledge-hammer  blows  of  the  air,  — 
a  machine  that  is  the  flimsiest  vehicle  in  which 
man  has  risked  his  life,  composed,  as  it  is,  of 
fragile  wires,  the  lightest  wood  cut  as  finely  as 
possible,  and  fabric  that  is  affected  by  varia- 
tions in  the  weather. 


THE   PERILS   OF   FLYING       181 

In  some  of  the  tragedies  of  the  flying-machine 
the  propeller  and  the  motor  have  each  played 
their  part.  Lieutenant  Selfridge's  death  at  Fort 
Myer  on  August  17,  1908,  was  due  to  the  snap- 
ping of  a  propeller  blade,  which  struck  a  loose 
wire,  an  accident  that  for  months  crippled 
Orville  Wright,  who  was  piloting  the  machine. 
This,  of  course,  was  not  due  to  any  inherent 
defect  in  the  propeller.  Indeed,  the  Wright 
propellers,  because  of  their  low  speed  (four 
hundred  to  five  hundred  revolutions  a  minute), 
are  probably  the  safest  in  use.  The  propellers 
of  most  monoplanes  and  biplanes  travel  at 
speeds  as  high  as  fifteen  hundred  revolutions 
a  minute,  or  about  as  fast  as  an  electric  fan. 
Propellers  mean  more  to  an  aeroplane  than 
stout  axles  on  an  automobile;  for  if  a  flying- 
machine  stops  it  must  glide  down.  Nearly 
every  contestant  at  a  flying-machine  meeting 
is  equipped  with  spare  propellers,  which  are  as 
near  alike  as  brains  and  hands  can  make  them. 
Yet  the  same  engine  will  not  be  able  to  turn 
two  propellers  seemingly  alike  at  the  same 
speed.  Why?  Because  man  can  make  steel, 
but  he  cannot  make  wood.  That  is  grown 


1 82    THE    NEW   ART    OF    FLYING 

by  nature.  And  because  woods  from  different 
trees  are  not  alike  the  propellers  formed  from 
them  are  not  alike.  Untraceable  and  insur- 
mountable variations  create  the  differences. 
In  aeroplaning  science  success  or  failure  de- 
pends on  just  such  slight  differences. 

The  propeller's  mechanical  cousin,  the  motor, 
is  also  not  what  it  ought  to  be.  At  very  great 
heights  it  is  impossible  to  obtain  adequately 
high  compressions  in  the  motor  cylinders. 
Hence  the  motor  stops,  and  the  aviator  must 
glide  down,  —  vol  plane,  as  the  French  call 
it.  Such  glides  can  be  made  with  comparative 
safety  if  the  pilot  is  skilful.  Occasionally  it 
happens  that  motor  stoppages  have  been  the 
cause  of  death.  It  was  the  stopping  of  his 
motor  that  killed  Leblon  at  San  Sebastian  on 
April  2,  1910,  and  Van  Maasdysk  at  Amster- 
dam on  August  22,  1910. 

To  prevent  such  accidents,  Mr.  Edwin  Gould 
in  1910  offered  through  the  Scientific  American 
a  prize  of  $15,000  to  the  designer  and  demon- 
strator of  a  successful  machine  equipped  with 
more  than  one  motor,  the  arrangement  being 
either  such  that  should  one  motor  be  disabled 


Fig.  69.— A  glimpse  through  a  Wright  biplane.    The 
two  planes  are  trussed  together  like  the  corre- 
sponding members  of  a  bridge,  so   as 
to  obtain  great  strength 


THE    PERILS   OF    FLYING       183 

another  can  be  immediately  thrown  into  gear, 
or  that  if  all  the  motors  should  be  running  si- 
multaneously the  stoppage  of  one  will  not  nec- 
essarily leave  the  apparatus  without  power. 
The  progress  which  has  been  made  since  the 
Wright  Brothers  gave  us  the  first  success- 
ful man-carrying  motor-driven  aeroplane  can 
hardly  be  called  scientific  progress.  Much  of 
it  has  been  progress  of  the  trial  and  error  vari- 
ety, very  costly  and  not  always  productive  of 
valuable  results.  It  may  be  retorted  that,  de- 
spite the  highly  scientific  experiments  of  Langley 
and  Maxim,  we  really  owe  the  successful  ma- 
chine to  such  men  as  the  Wright  Brothers,  who 
are  not  profound  mathematicians  but  skilful, 
practical  mechanics.  If  the  whole  truth  were 
known  about  the  years  of  patient  experiment- 
ing which  finally  led  the  Wright  Brothers  to 
the  invention  of  a  successful  flying-machine,  it 
would  probably  be  discovered  that  they  were 
no  less  scientific  in  their  methods  than  was 
Langley  himself. 

The  problem  of  building  a  flying-machine  is 
in  quite  a  different  position  from  what  it  was. 
If  flying-machines  are  not  to  be  subjected  to 


1 84    THE    NEW   ART   OF    FLYING 

frequent  accidents  and  are  to  be  made  acces- 
sible to  the  million,  the  sooner  aeronauts  learn 
engineering  the  better.  Not  until  engineers  are 
employed  to  design  and  build  flying-machines 
shall  we  be  able  to  skim  the  air  as  safely  as  we 
now  roll  along  the  ground  in  motor-cars. 


CHAPTER    XI 

THE   FLYING-MACHINE   IN   WAR 

UNLIKE  any  battle  that  has  ever  been  fought 
in  the  world's  history,  the  battle  of  the  future 
will  be  a  conflict  waged  in  three  dimensions. 
Long  before  its  artillery  will  have  volleyed 
and  thundered,  each  great  military  power  will 
have  endeavoured  to  secure  the  command  of 
the  air  by  building  more  dirigible  airships  and 
aeroplanes  than  its  rivals.  The  fighting  arm 
of  a  nation  will  henceforth  be  extended  not 
merely  over  land  and  sea,  but  upward  into  the 
hitherto  unconquerable  air  itself.  Of  all  this 
we  had  some  indication  during  the  remarkable 
French  military  manoeuvres  of  1910.  Then  for 
the  first  time  aeroplanes  were  tested  under  condi- 
tions that  approximated  those  of  actual  warfare. 
To  the  laymen  the  aeroplane's  chief  function 
in  this  battle  of  the  future  would  seem  to  be 
the  dropping  of  explosives  on  a  hapless  and 
helpless  army  below.  The  military  strategist 
knows  better.  In  the  first  place  he  knows  that 


1 86    THE    NEW    ART   OF    FLYING 

the  actual  amount  of  damage  which  could  thus 
be  inflicted  would  be  disappointingly  small.  A 
hole  may  be  torn  in  the  ground;  the  windows 
of  a  few  buildings  may  be  broken;  a  battle- 
ship's superstructure  may  be  blown  away;  but 
that  wholesale  destruction  of  life  and  property 
which  would  seem  obviously  to  follow  from 
the  mere  existence  of  military  flying-machines, 
freighted  with  bombs  and  grenades,  is  not  to 
be  looked  for.  Even  were  it  possible  thus  to 
destroy  part  of  a  stronghold,  the  difficulty  of 
hitting  the  object  aimed  at  is  nearly  insur- 
mountable. Every  small  boy  has  attempted  to 
hit  some  passer-by  in  the  street  with  a  missile 
hurled  from  a  third-story  window.  Usually 
he  failed,  because  the  target  was  moving  and 
because  the  wind  deflected  the  projectile.  The 
air-marksman  is  much  worse  off.  Seated  in  a 
craft  which  is  not  only  skimming  at  a  speed 
hardly  less  than  thirty-five  miles  an  hour  and 
possibly  as  great  as  eighty  miles  an  hour,  but 
skimming  at  a  height  of  perhaps  half  a  mile, 
the  chance  that  he  will  ever  be  able  to  hit  his 
target  by  making  the  proper  allowance  for  the 
horizontal  momentum  which  his  bomb  would 


THE  FLYING-MACHINE  IN  WAR    187 

receive,  as  well  as  for  the  prevailing  wind, 
seems  wofully  remote.  If  bombs  are  to  be 
dropped  on  forces  below,  it  must  be  by  means 
of  tubes  which  will  both  project  and  direct  the 
missile  and  which  will  be  provided  with  wind 
gauges  and  height  indicators  for  the  proper 
guidance  of  the  marksman.  We  must  not  allow 
ourselves  to  be  misled  by  the  skill  displayed  at 
flying  exhibitions  in  dropping  oranges  on  mini- 
ature battleships.  Oranges  are  not  bombs,  nor 
are  the  heights  at  which  they  are  dropped  the 
half  mile  at  which  a  military  aeroplane  must 
soar  if  it  is  to  elude  gun-fire. 

Nevertheless  some  such  possibility  may  have 
been  at  the  bottom  of  the  declaration  signed 
by  the  delegates  of  the  United  States  to  the 
Second  International  Peace  Conference  held  at 
The  Hague  in  1907,  —  a  declaration  which 
prohibited  the  discharge  of  projectiles  and  ex- 
plosives from  the  air.  The  declaration  reads: 

"  The  contracting  powers  agree  to  prohibit, 
for  a  period  extending  to  the  close  of  the  Third 
Peace  Conference,  the  discharge  of  projectiles 
and  explosives  from  balloons  or  by  other  new 
methods  of  a  similar  nature." 


1 88    THE    NEW   ART    OF    FLYING 

The  countries  which  did  not  sign  the  decla- 
ration forbidding  the  launching  of  projectiles 
and  explosives  from  air-craft  were:  Germany, 
Austria-Hungary,  China,  Denmark,  Ecuador, 
Spain,  France,  Great  Britain,  Guatemala,  Italy, 
Japan,  Mexico,  Montenegro,  Nicaragua,  Para- 
guay, Roumania,  Russia,  Servia,  Sweden, 
Switzerland,  Turkey,  Venezuela. 

To  be  effective,  a  bomb  must  be  fairly  large. 
Moreover,  a  considerable  supply  of  bombs  must 
be  available.  The  aeroplane  is  a  thing  of  com- 
parative lightness.  It  cannot  carry  much  am- 
munition of  that  sort.  Hence,  even  admitting 
the  possibility  of  dropping  explosives  upon  any 
desired  spot,  the  destruction  wrought  must  nec- 
essarily be  limited  in  extent.  Lastly,  there  is 
also  considerable  danger  in  unbalancing  the 
machine,  by  the  sudden  removal  of  the  load 
from  one  side. 

During  the  French  manoeuvres  of  1910  no 
attempt  seems  to  have  been  made  to  drop 
explosives  from  either  airships  or  aeroplanes, 
an  omission  which  implies  the  ineffective- 
ness of  that  mode  of  attack.  In  the  war  of 
the  future  the  aeroplane  will  be  employed 


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THE  FLYING-MACHINE  IN  WAR    189 

primarily  for  the  transmission  of  orders 
and  despatches;  for  discovering  an  enemy  in 
a  region  in  which  his  presence  is  suspected,  his 
strength  and  the  disposition  of  his  forces  being 
unknown;  for  ascertaining  the  strength  of  an 
enemy  at  points  where  he  is  known  to  be  lo- 
cated; and  for  collecting  sufficient  information 
to  permit  siege  guns  to  plant  their  shells  where 
they  will  be  most  effective.  In  other  words,  the 
future  military  aeroplane  will  do  the  work  of 
a  scouting  force;  for  its  chief  function  will  be 
that  of  reconnaissance.  Two  men  will  be 
seated  in  its  frame,  one  to  pilot  the  machine, 
and  one  to  sketch  and  photograph  the  terrane 
below.  From  the  trained  eye  of  the  spy  in  the 
air  nothing  will  be  concealed.  He  will  be  like 
a  vulture  wheeling  in  the  blue,  watching  for 
carrion  below.  The  click  of  his  camera-shutter 
may  be  a  death-knell,  for  it  will  record  instan- 
taneously the  position  of  some  battery  cun- 
ningly hidden  behind  a  ridge,  an  earthwork 
thrown  up  across  a  pass,  a  stream  spanned  by 
military  pontoon  bridges.  His  pencil,  when  it 
touches  the  page  of  a  notebook,  may  spell  the 
death  sentence  of  a  regiment;  for  it  will  un- 


1 9o    THE    NEW   ART   OF    FLYING 

erringly  note  those  details  of  position  and  num- 
bers which  the  photographic  plate  may  not  be 
able  to  register.  When  he  has  learned  all  that 
he  can  learn,  he  signals  his  companion  to  re- 
turn. Hardly  two  hours  may  have  elapsed  since 
he  was  despatched  on  his  quest.  Yet  within 
that  time  he  may  be  able  to  give  his  command- 
ing officer  information  that  a  regiment  of  cav- 
alry could  not  have  gathered  with  almost  unlim- 
ited time. 

Both  Generals  Picquart  and  Meunier,  the 
opposing  commanders  during  the  French  ma- 
noeuvres of  1910,  expressed  their  satisfaction 
with  the  performance  of  aerial  scouts.  The 
machines  were  sent  up  practically  whenever 
they  were  ordered  to  do  so.  What  is  more, 
the  aviators  carried  out  orders  to  the  letter,  and 
often  under  very  unfavourable  weather  condi- 
tions. It  was  doubted  at  first  whether  they 
would  be  able  to  report  with  any  degree  of 
definiteness  upon  the  position  and  number  of 
the  enemy.  At  a  height  of  fifteen  hundred  feet, 
it  seems  quite  possible,  however,  for  a  prac- 
tised man  to  discover  the  character  of  the 
troops  below  him  and  to  ascertain  whether  they 


THE  FLYING-MACHINE  IN  WAR    191 

are  infantry,  cavalry,  or  artillery.  Artillery  is 
easily  enough  distinguished  by  the  intervals  be- 
tween the  horses.  By  counting  the  number  of 
gun  caissons  the  strength  of  the  battery  can  be 
ascertained.  The  strength  of  cavalry  and  in- 
fantry is  arrived  at  by  counting  the  companies 
or  other  group  formations. 

During  the  manoeuvres  in  question  it  was 
sometimes  difficult  at  the  first  glance  to  gain 
definite  information  of  troops  in  battle  forma- 
tion, and  at  times  it  was  possible  to  distinguish 
friend  from  foe  only  by  the  direction  of  fire. 
Lieutenant  Sido,  a  French  army  officer  and 
aerial  scout,  in  commenting  upon  the  possibility 
of  discovering  at  a  very  great  height  the  posi- 
tion of  an  enemy's  forces,  stated  that  a  man 
who  goes  up  in  an  aeroplane  for  the  first  time 
cannot  distinguish  anything  below  him;  that 
many  flights  are  necessary  before  he  can  form 
a  judgment  of  the  terrane  below;  that  good 
eyesight,  coupled  with  experience,  are  neces- 
sary; that  field  glasses  are  needed  only  rarely; 
and  that  at  a  very  great  height  cavalry  is  some- 
what harder  to  make  out  than  artillery. 

Although   aeroplanes  carrying  but   a   single 


i92    THE    NEW   ART   OF   FLYING 

man  did  much  valuable  work  during  the  ma- 
noeuvres, it  is  generally  agreed  that  the  military 
aeroplane  must  carry  at  least  two  men,  one  of 
whom  shall  act  as  a  pilot,  and  the  other  as  an 
observer.  As  the  field  of  the  military  aero- 
plane is  extended,  it  is  very  likely  that  non- 
commissioned officers,  and  even  ordinary  sol- 
diers, will  be  entrusted  with  the  piloting  of  the 
machine.  The  observer  must  always  be  an  in- 
telligence officer  of  experience.  Lieutenant 
(now  Captain)  Bellenger,  who  distinguished 
himself  by  his  effective  reconnaissances  in  a 
Bleriot,  maintains  that  one  man  will  answer 
for  ordinary  scouting.  When  it  is  considered, 
however,  that  the  machine  is  to  be  controlled, 
that  maps  are  to  be  read,  that  the  enemy's 
strength  and  disposition  are  to  be  discovered, 
that  notes  and  sketches  are  to  be  made,  it 
seems  obvious  that  more  than  one  man  will  be 
required. 

It  may  be  doubted  whether  the  aeroplane 
will  entirely  supplant  the  usual  forces  employed 
for  reconnaissance.  The  mist  which  usually 
conceals  the  ground  early  in  the  morning  will 
probably  interfere  seriously  with  the  activities 


Photograph  by  Edwin  Levick 

Fig.  71. — A  biplane  that  came  to  grief  because  of 
defective  lateral  control 


THE  FLYING-MACHINE  IN  WAR    193 

of  the  aerial  scout,  not  to  mention  ordinary 
fogs.  Night  marches  and  cavalry  raids  will 
probably  be  necessary  as  they  have  been  in 
the  past,  and  troops  will  mask  themselves  as 
they  always  have  by  natural  and  artificial 
concealments. 

No  doubt  new  stratagems  will  be  devised  to 
deceive  the  aerial  eye.  It  is  conceivable  that  a 
regiment  may  group  itself  in  battalion  or  even 
brigade  form,  so  that  its  strength  may  be  over- 
estimated. Other  stratagems  suggest  them- 
selves, such  as  the  feigned  movements  which 
completely  misled  the  observers  in  dirigible 
airships  during  the  German  army-manoeuvres 
of  1910. 

It  is  highly  advisable  that  the  aeroplane  be 
fitted,  if  possible,  with  some  form  of  wireless 
telegraph  apparatus,  so  that  the  commanding 
officer  may  be  kept  fully  informed  of  each  new 
discovery.  The  necessity  of  reporting  in  per- 
son means  the  return  of  the  aeroplane  to  head- 
quarters. Up  to  the  present  time,  no  very 
successful  attempt  has  been  made  in  this  direc- 
tion, although  the  success  of  the  wireless  instal- 
lation on  the  dirigible  "  Clement-Bayard  II  " 


i94    THE    NEW    ART    OF    FLYING 

would  seem  to  indicate  that  the  problem  is  not 
beyond  solution. 

For  ordinary  reconnaissance  on  the  battle- 
field elaborate  notes  are  not  essential.  The 
notes  that  Captain  Bellenger  took  were  of 
the  most  meagre  character,  —  simply  sufficient 
to  refresh  his  memory.  They  were  mere  mem- 
oranda which  read,  for  example,  "  7  h.  47  m. 
Mortvillers,  3  batteries."  Such  a  note  was  all 
that  he  required  when  making  his  oral  report 
to  refresh  his  memory.  For  siege  work,  on 
the  other  hand,  Bellenger  insists  on  much  more 
detailed  information.  In  reconnoitring  of  that 
character  the  chief  work  to  be  performed  by 
the  man  in  the  air  will  be  the  precise  indica- 
tion of  the  point  to  be  shelled.  An  error  of 
only  one  hundred  and  fifty  feet  in  giving  that 
position  may  nullify  the  besieging  commander's 
best  efforts.  Reconnaissances  in  force  to  as- 
certain the  enemy's  disposition,  a  tactical  neces- 
sity which  may  require  a  detachment  of  sev- 
eral thousand  men  from  the  main  army  for  a 
considerable  period  of  time  will  probably  be 
of  infrequent  occurrence  in  the  future  war- 
fare. An  aeroplane  will  accomplish  the  same 


THE  FLYING-MACHINE  IN  WAR    195 

result  in  a  fraction  of  the  time.  One  of 
the  bloodiest  encounters  the  world  has  ever 
seen  was  the  Japanese  attack  on  "  203  Meter 
Hill."  Yet  the  sole  purpose  of  that  great 
slaughter  was  the  placing  of  two  or  three  men 
at  the  summit  of  the  hill  to  direct  the  fire  of  the 
Japanese  siege  guns  upon  the  Russian  fleet  in 
the  harbour  of  Port  Arthur. 

Major  G.  O.  Squier  of  the  United  States 
Signal  Corps  has  pointed  out  that  the  realisa- 
tion of  aerial  navigation  for  military  purposes 
brings  forward  new  questions  as  regards  the 
limitation  of  frontiers.  As  long  as  military 
operations  are  confined  to  the  surface  of  the 
earth,  it  has  been  the  custom  to  protect  the 
geographical  limits  of  a  country  by  ample 
preparations  in  time  of  peace,  such  as  a  line 
of  fortresses  properly  garrisoned.  At  the  out- 
break of  war  these  boundaries  represent  real 
and  definite  limits  to  military  operations.  Ex- 
cursions into  the  enemy's  territory  usually  re- 
quire the  backing  of  a  strong  military  force. 
Under  the  new  conditions,  however,  these  geo- 
graphic boundaries  no  longer  offer  the  same 
definite  limits  to  military  movements.  With  a 


196    THE   NEW   ART   OF   FLYING 

third  dimension  added  to  the  theatre  of  opera- 
tions, it  will  be  possible  to  pass  over  this  boun- 
dary on  rapid  raids  for  obtaining  information, 
accomplishing  demolitions,  etc.,  returning  to 
safety  in  a  minimum  time.  Major  Squier, 
therefore,  regards  the  advent  of  military  scouts 
of  the  air  as,  in  a  measure,  obliterating  pres- 
ent national  frontiers  in  conducting  military 
operations. 

Is  the  enemy  altogether  defenceless?  Can 
he  offer  no  resistance?  It  is  inconceivable  that 
he  shall  lie  at  the  mercy  of  a  great  artificial 
vulture,  as  helpless  as  a  carcass.  Undoubtedly 
he  will  have  his  special  artillery,  —  field  pieces 
so  constructed  that  they  can  be  elevated  for 
high  angle  fire.  Against  that  military  bird  of 
prey  which  he  sees  hovering  far  above  him  and 
whose  errand  he  divines  only  too  well,  he  will 
train  this  weapon.  If  his  whistling  shrapnel 
should  strike  a  motor,  a  propeller  blade,  or  an 
ignition  device,  if  it  should  cut  a  tiller  rope  or 
splinter  a  steering  rod,  that  great  bird  above 
him  must  glide  down,  wounded  at  least.  It  is 
not  necessary  to  kill  the  pilot,  but  merely  to 
strike  a  vital  part  of  the  driving  mechanism. 


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THE  FLYING-MACHINE  IN  WAR    197 

The  spy  in  the  air  may  glide  down  in  safety; 
but  his  information  is  lost  to  his  commanding 
officer.  The  question  arises,  can  the  aeroplane 
be  struck  so  easily?  Probably  not.  A  moving 
object  is  always  difficult  to  hit,  but  trebly  so 
when  it  soars  half  a  mile  up  in  the  sky. 

Such  guns  are  made  in  Germany  by  Krupp 
and  by  the  Rheinische  Metallwaaren  und  Ma- 
schinenfabrik,  of  Diisseldorf.  The  guns  have 
small  bores  and  use  light  projectiles,  so  that 
they  can  be  fired  quickly.  The  barrels  are  com- 
paratively long,  so  that  a  high  initial  velocity 
and  a  low  trajectory  are  obtained.  Telescope 
sights  and  a  range  finder  are  provided,  the 
latter  fitted  with  an  arrangement  which  gives 
the  necessary  elevation  as  the  distance  is  read 
off. 

The  ordinary  Krupp  field  gun  has  a  6.5  cm. 
bore  (Fig.  73),  and  is  fitted  with  an  hydraulic 
brake  and  a  spring  recoil.  A  coiled  spring  is 
provided  to  balance  the  gun  as  it  is  pointed 
above  the  horizontal.  The  upper  part  of  the 
gun-carriage  is  movable,  and  the  wheels  can  also 
be  given  a  half-turn  away  from  the  body,  which 
assists  in  quick  aiming.  This  equipment  weighs 


198    THE    NEW    ART   OF    FLYING 

875  kilos,  352  kilos  of  this  being  in  the  gun, 
523  kilos  in  the  carriage.  The  projectile 
weighs  4  kilos  —  about  81  Ibs.  13  oz.  The  ini- 
tial velocity  is  given  as  620  m.  —  roughly 
2,034  ft.  a  second;  the  extreme  range,  8,650  m. 
—  9,450  yards;  and  the  height  of  fire  obtain- 
able, 5,700  m.  —  roughly  18,700  ft.  The  gun 
can  be  elevated  through  an  angle  of  70  degrees 
above  the  horizontal,  and  depressed  5  degrees 
below  it,  and  it  can  be  revolved  right  round 
through  an  angle  of  360  degrees. 

A  heavier  type  of  Krupp  field  gun  (Fig.  74) 
has  a  bore  of  7.5  cm.,  and  weighs  when  ready 
for  firing  1,065  kilos.  The  weight  of  the  pro- 
jectile is  5.5  kilos  —  about  12  Ibs.  2  oz.  The 
initial  velocity  is  stated  to  be  625  m.  per  sec- 
ond, and  9,100  m.  and  6,300  m.  are  given  as  the 
extreme  range  and  height  attained  at  trials. 
The  motor-car  on  which  the  weapon  is  carried 
is  designed  for  an  average  speed  of  45  kilome- 
tres—  2%y2  miles  an  hour,  and  weighs  3,250 
kilos  —  7,163  Ibs.  —  without  the  gun.  It  car- 
ries 62  projectiles  under  the  seats,  and  is 
propelled  by  a  50  horse-power  motor.  It  is 
steadied  during  firing  by  a  special  arrangement 


THE  FLYING-MACHINE  IN  WAR    199 

which  presses  the  platform  against  the  axles. 
The  gun  can  be  elevated  to  an  angle  of  75 
degrees  from  the  horizontal,  and  can  be  re- 
volved through  a  complete  circle. 

A  10.5  cm.  naval  gun  (Fig.  75)  is  also  made 
by  Krupps.  It  weighs  3,000  kilos  when  ready 
for  firing,  the  projectile  18  kilos,  the  gun  1,400, 
the  carriage  1,600.  Its  initial  velocity  is  700  m. 
per  second,  and  13,500  m.  and  11,400  m.  are 
given  as  the  extreme  range  and  height  attain- 
able. As  in  the  case  of  the  7.5  cm.  gun,  it  can 
be  elevated  through  an  angle  of  75  degrees 
from  the  horizontal,  and  revolved  through  a 
complete  circle.  All  these  three  guns  are  35 
calibres  long. 

The  guns  made  by  the  Diisseldorf  firm  are 
of  a  somewhat  different  construction.  The  bore 
is  5  cm.,  and  the  barrel  is  30  calibres  long.  The 
gun  is  worked  from  a  centre  pivot  by  a  hand- 
wheel  and  weighs  140  kilos  —  400  kilos  with 
shield.  It  can  be  elevated  to  an  angle  of  70 
degrees  above  the  horizontal,  and  depressed 
5  degrees  below  it,  and  can  be  revolved  through 
a  complete  circle.  The  total  weight  of  the  gun, 
ammunition,  five  men  and  car  comes  to  3,200 


200    THE    NEW    ART    OF    FLYING 

kilos.  The  car  is  built  at  the  factory  of  Ehr- 
hardt,  at  Zella,  and  is  driven  by  a  motor  of  50 
to  60  horse-power,  which  propels  it  at  a  normal 
speed  of  45  kilometres  per  hour.  It  is  said  to 
be  capable  of  negotiating  gradients  of  22  per 
cent  even  on  bad  roads.  The  whole,  including 
the  wheels,  can  be  protected  by  nickel-steel  plate 
shields. 

During  the  French  manoeuvres  of  1910  a 
special  gun  was  used  for  the  repulsion  of  air- 
ships and  aeroplanes,  the  invention  of  Captain 
Houbernat.  It  was  a  weapon  of  75  millimetres 
(3  inches)  diameter  carried  on  an.  automobile. 
The  maximum  elevation  of  fire  was  66  degrees. 
The  piece  was  so  mounted  that  it  could  be 
swung  down  for  its  whole  length  with  the 
muzzle  beside  the  driver  of  the  car.  When  ele- 
vated, the  entire  weight  of  the  piece  was  thrown 
on  the  rear  of  the  motor-car.  Hence  it  was 
necessary  to  stake  down  the  front  wheels.  The 
weapon  had  a  range  of  5,000  metres  (3  miles). 
The  projectiles  fired  were  Robin  shells  which  ex- 
plode at  a  maximum  elevation  of  2,500  metres 
(7,200  feet).  Besides  this  piece,  a  mitrailleuse 
was  used  of  the  usual  type  employed  by  French 


THE  FLYING-MACHINE  IN  WAR    201 

infantry  and  cavalry,  but  modified  so  that  it 
could  be  elevated  at  a  high  angle  and  fired  from 
an  automobile  if  necessary. 

The  question  of  ammunition  most  suitable 
for  guns  is  also  receiving  attention  in  Germany. 
The  Diisseldorf  firm  mentioned  has  introduced 
a  combined  shrapnel  and  ordinary  shell  for  use 
against  both  dirigibles  and  aeroplanes.  This 
new  form  of  shrapnel  differs  from  that  which  is 
ordinarily  fired  in  so  far  as,  after  the  explosion 
of  the  shrapnel  part,  the  shell  part  is  carried 
on  to  the  target,  or  to  the  ground,  where  it  det- 
onates, giving  off  in  its  flight  an  observable 
cloud  of  smoke.  A  somewhat  similar  projectile 
is  also  made  by  the  Krupps.  The  trail  of 
smoke  serves  the  purpose  of  indicating  how  close 
the  projectile  came  to  its  mark  (Figs.  76  and 

77)- 

Not  upon  such  artillery  and  shells  and  shrap- 
nel will  the  enemy  rely,  but  on  aeroplanes  and 
airships  of  his  own.  He  must  fight  steel  with 
steel.  When  he  sees  a  black  speck  in  the  sky, 
moving  toward  him,  he  gives  a  quick  command. 
A  monoplane  or  a  biplane,  perhaps  two,  start 
with  a  whirr  from  his  camp  and  soar  to  meet 


202    THE    NEW   ART    OF    FLYING 

that  speck.  When  machine  encounters  machine 
in  the  sky,  what  will  happen?  They  dare  not 
ram  each  other.  That  would  mean  the  inevit- 
able destruction  of  both;  for  the  two  would 
surely  fall,  a  mass  of  twisted  and  splintered 
metal  and  wood.  They  must  fire  at  each  other. 
But  with  what?  Not  with  revolvers  or  rifles, 
for  their  range  is  too  small  for  effective  shoot- 
ing at  an  aeroplane  wheeling  around  some 
thousands  of  yards  away;  not  with  a  field-piece, 
for  it  could  not  be  carried  on  so  light  a  contriv- 
ance; but  with  a  machine-gun  of  especially  light 
construction,  a  mitrailleuse  which  will  pour  forth 
so  many  hundred  shots  a  minute  in  a  steady 
stream,  like  a  jet  of  water  spouting  from  a 
hose.  That  battle  in  the  sky  will  be  won  by 
the  swiftest  and  most  readily  controlled  flying- 
machine,  —  by  the  aeroplane,  in  a  word,  which 
can  run  and  choose  its  own  position  and 
range. 

The  question  may  well  be  asked:  What  will 
be  the  relation  of  dirigible  to  aeroplane?  Will 
the  one  type  displace  the  other?  Both  types 
will  probably  be  necessary.  The  dirigible  and 
the  aeroplane  will  bear  to  each  other  the  rela- 


THE  FLYING-MACHINE  IN  WAR    203 

tion  of  battleship  to  torpedo  boat.  In  actual 
war  each  combatant  will  have  a  fleet  of  both 
airships  and  aeroplanes.  When  an  enemy  ap- 
pears it  will  be  the  first  duty  of  the  opposing 
fleet  to  attack  him.  The  home  fleet  will  have  a 
certain  advantage  because  it  will  be  nearer  its 
base.  It  is  not  likely  that  an  attacking  fleet  will 
sail  over  an  enemy's  country  unless  it  is  able  to 
destroy  the  home  fleet. 

What  chance  has  the  dirigible  against  the 
aeroplane  in  an  aerial  battle?  Because  of  its 
greater  speed  the  aeroplane  has  the  advantage 
of  fighting  or  running.  Moreover,  the  dirigible 
being  a  most  expensive  machine,  there  are  al- 
ways likely  to  be  more  aeroplanes  than  air- 
ships, so  that  many  aeroplanes  can  be  opposed 
to  a  single  dirigible,  just  as  many  torpedo 
boats  are  sent  against  a  single  battleship  on 
the  theory  that  one  at  least  will  deal  a  fatal 
blow. 

Its  great  speed  gives  the  aeroplane  an  im- 
measurable advantage  over  the  dirigible  even 
in  scouting.  Suppose  that  a  frontier  several 
miles  long  is  patrolled  by  a  fleet  of  dirigibles, 
and  suppose  that  a  considerable  number  of  hos- 


204    THE    NEW   ART    OF    FLYING 

tile  aeroplanes  is  available  to  ascertain  the 
position  and  strength  of  the  enemy  beyond  that 
frontier.  No  reasonable  number  of  dirigibles 
could  alone  protect  that  frontier  from  invasion. 
The  blockade  can  always  be  run.  However  well 
the  line  may  be  protected,  there  will  be 
spaces  where  the  aeroplane  can  cross  and 
recross  after  having  taken  all  the  observations 
required. 

For  actual  fighting  purposes  the  aeroplane 
cannot  as  yet  be  reckoned  with.  It  can  be  armed 
only  with  the  lightest  gun  and  can  carry  only 
a  very  limited  amount  of  ammunition  and  men. 
The  dirigible,  on  the  other  hand,  can  carry  a 
crew  of  twenty-six  and  can  be  fitted  with  guns 
much  above  rifle-calibre.  It  can  remain  in  the 
air  thirty  or  forty  hours,  and  in  that  time  travel 
several  hundred  miles.  When  the  aeroplane 
can  carry  a  couple  of  fighting  men  in  addition 
to  the  pilot,  and  these  can  be  armed  with  some- 
thing in  the  nature  of  a  machine-gun,  the  effi- 
ciency of  aeroplanes  will  be  far  increased  if 
they  can  cruise  in  fleets  against  isolated  dirigi- 
bles. The  small  target  and  high  speed  of  the 
aeroplane  will  be  in  its  favour,  even  though  its 


THE  FLYING-MACHINE  IN  WAR    205 

opponent  will  be  more  heavily  armed.  More- 
over the  inevitable  confusion  attending  a  com- 
bat waged  upwards  and  downwards  and  on  all 
sides  should  offer  many  a  chance  to  a  daring 
fighter  of  delivering  a  telling  blow. 

It  has  been  urged  that  if  the  aeroplane  once 
gets  above  the  dirigible  the  fate  of  the  latter 
is  sealed;  for  the  gas  bag  prevents  the  dirigible 
from  firing  at  the  aeroplane.  It  may  well  be 
that  gun-platforms  will  be  arranged  on  top 
with  a  conning-tower  projecting  from  the  car 
below,  through  the  gas  bag.  Such  a  construc- 
tion has  been  proposed  in  Germany.  At  pres- 
ent the  dirigible  can  ascend  to  heights  which 
the  aeroplane  has  not  yet  reached.  The  rarity 
of  air  at  altitudes  of  over  a  mile  has  an  im- 
portant effect  on  the  operation  of  the  aeroplane 
engine.  Most  of  the  men  who  have  soared  to 
great  heights  in  aeroplanes  have  found  that 
their  motors  stopped  at  a  certain  elevation,  and 
a  motor  that  stops  places  the  pilot  in  the  posi- 
tion of  a  balloonist  whose  gas  has  leaked  away. 
If  the  aeroplane  can  choose  its  own  range  be- 
cause of  superior  speed,  the  dirigible  can  at 
least  choose  its  own  elevation.  Yet  even  here 


206    THE    NEW   ART   OF    FLYING 

there  are  limitations  to  be  observed.  As  a 
dirigible  rises  its  gas  expands.  To  prevent  the 
bursting  of  the  envelope,  gas  must  be  allowed 
to  escape.  Hence  when  the  dirigible  drops 
again  to  a  lower  level,  its  ascensional  power 
has  been  considerably  curtailed. 

Command  of  the  air,  like  command  of  the 
sea,  will  depend  on  men  and  material.  With- 
out men  of  courage  and  skill,  flying-machines 
are  useless.  Without  efficient  flying-machines, 
on  the  other  hand,  it  is  obvious  that  men  cannot 
fly.  The  situation  is  much  the  same  in  that  re- 
spect as  in  naval  affairs.  England  has  domi- 
nated the  sea  because  she  has  had  the  ships 
and  a  well-trained  industrious  body  of  civilians 
to  fight  them.  Acquisition  of  material  is  merely 
a  matter  of  spending  money.  The  nation  that 
spends  the  most  money  will  have  the  most 
numerous  and  best  equipped  air  navy.  In  the 
case  of  war  in  the  air,  as  at  sea,  success  will 
depend  not  only  on  abundant  material,  but  on 
the  ability  to  supply  wastage  of  war,  which  is 
enormous  and  increases  in  enormity  as  the  ma- 
terial becomes  more  complicated  and  costly. 
In  matters  of  armament,  however,  cost  is  not 


THE  FLYING-MACHINE  IN  WAR    207 

the  guiding  principle.  Nothing  is  so  expensive 
as  defeat,  and  to  avoid  defeat  the  most  efficient 
aircraft  must  be  provided  in  sufficient  numbers. 
Battles,  aerial  or  terrestrial,  are  won  as  much 
by  money  as  by  hard  fighting. 


CHAPTER   XII 

SOME   TYPICAL   BIPLANES 

ALL  biplanes,  no  matter  by  whom  designed, 
have  certain  features  in  common.  Besides  the 
two  superposed  supporting  surfaces  from  which 
they  take  their  name,  they  all  have  a  horizontal 
rudder  or  elevator,  by  means  of  which  the  ma- 
chine is  guided  up  or  down  and  is  prevented 
from  pitching;  a  vertical  rudder,  by  means  of 
which  the  machine  is  kept  on  an  even  course 
and  turned  to  the  right  or  to  the  left;  and 
some  means  by  which  the  amount  of  main  sur- 
face exposed  to  the  pressure  of  the  air  can  be 
varied,  so  as  to  keep  the  machine  in  balance 
from  side  to  side.  To  these  essential  elements 
a  tail,  consisting  of  a  small  horizontal  surface, 
is  usually  added,  because  it  serves  to  steady 
the  machine  in  flight. 

Just  how  these  elements  shall  be  disposed  is 
a  matter  of  more  or  less  difference  of  opinion 
among  biplane  designers,  and  this  difference  of 
opinion  has  given  us  the  various  biplanes  of  the 


SOME   TYPICAL    BIPLANES     209 

Wrights,  Curtiss,  Farman,  Goupy,  Sommer, 
Breguet,  and  others.  Biplanes  as  a  class  fol- 
low the  lines  of  the  Wright  machine.  It  is  here 
impossible  and  unnecessary  to  describe  in  de- 
tail all  the  biplanes  in  use  at  the  present  day. 
For  our  purpose  it  will  be  quite  sufficient  to  con- 
fine ourselves  to  the  Wright,  Curtiss,  Farman, 
and  Sommer  machines,  inasmuch  as  they  rep- 
resent the  chief  systems  of  control  to  be  found 
in  the  two-surface  machine. 

THE  WRIGHT  BIPLANE 

The  two  supporting  surfaces  of  the  Wright 
machine  consist  of  canvas  stretched  over  and 
under  ribs  of  spruce.  At  a  point  near  the  centre 
these  surfaces  are  three  inches  thick.  The 
dimensions  of  the  planes  vary.  In  the  earlier 
machines  they  measured  41  feet  in  spread, 
6.56  feet  in  depth,  and  538  square  feet  in  area. 
In  the  later  machines  the  spread  has  been  re- 
duced to  39  feet,  the  depth  to  5.5  feet,  and  the 
area  to  410  square  feet.  A  smaller  model  has 
also  been  designed  in  which  the  spread  has  been 
reduced  to  26  feet. 

In  the  first  Wright  machines  (Fig.  79)  the 


210    THE    NEW   ART   OF    FLYING 

horizontal  or  elevation  rudder  was  mounted  in 
front,  and  was  so  constructed  that  it  was  auto- 
matically curved  concavely  on  the  under  side 
when  elevated,  and  in  the  opposite  way  when 
depressed.  A  long  wooden  rod  connected  the 
horizontal  rudder  with  a  lever,  which  was  ma- 
nipulated by  the  operator's  left  hand  (Fig.  20). 
By  pulling  the  lever  toward  him  the  operator 
inclined  the  rudder  upward;  by  pushing  the 
lever  away  from  him  the  operator  depressed 
the  rudder. 

The  vertical  rudder,  which  not  only  served 
to  steer  the  machine  in  a  horizontal  plane  but 
also  to  prevent  it  from  spinning  on  a  vertical 
axis,  was  mounted  in  the  rear  of  the  machine  as 
at  present.  It  consisted  and  still  consists  of 
two  parallel  vertical  surfaces,  swung  by  a  lever 
in  the  operator's  right  hand.  By  pushing  the 
lever  away  from  him  the  operator  turns  the 
machine  to  the  left;  by  pulling  it  toward  him 
he  turns  the  machine  to  the  right. 

Side-to-side  balance  has  always  been  main- 
tained in  the  Wright  biplane  by  warping  the 
main  planes  in  the  manner  explained  in  Chap- 
ter V.  The  entire  front  of  the  two  supporting 


Fig.  75- — A  Krupp  10.5  cm.  naval  gun  for  repelling 
aircraft 


SOME   TYPICAL   BIPLANES     211 

surfaces  is  rigid;  but  the  rear  corners  are  mov- 
able.    The  central  sections  of  the  two  planes 
are  rigid  and  are  never  moved  in  balancing  the 
machine.    Only  the  rear  corners  of  both  planes 
play    any   part    in    controlling   the    apparatus. 
These  flexible  rear  corners  of  both  planes  are 
connected  by  means  of  cables  with  the  lever  in 
the  operator's  right  hand  (Fig.  20),  in  other 
words,  the  lever  which  controls  the  vertical  rud- 
der.    By  throwing  the  lever  from  side  to  side 
the  rear  corners  are  flexed  in  opposite  direc- 
tions;   in  other  words,  as  one  corner  of  one 
plane  is  bent  down,  the  other  corner  of  the 
same  plane  is  bent  up,  with  the  result  that  the 
entire  plane  is  given  what  the  Wrights  call  a 
"  helicoidal  warp."     The  same  lever  controls 
both  the  vertical  rudder  and  the  warping  of  the 
planes,  because  the  Wrights  found  that  as  the 
planes  were  bent  the  machine  would  spin  on  a 
vertical  axis,  as  explained  in  Chapter  V.    This 
lever  is  therefore  swung  in  a  circular  or  ellip- 
tical path  so  that  the  planes  are  warped  and 
the  vertical  rudder  swung  in  the  proper  direc- 
tion at  the  same  time. 

In  the  newer  Wright  biplanes  a  modified  form 


212    THE    NEW    ART    OF    FLYING 

of  lever  has  been  adopted  to  warp  the  wings 
and  turn  the  vertical  rudder,  the  principle,  how- 
ever, remaining  substantially  the  same.  The 
new  lever  is  provided  with  an  auxiliary  grip, 
which  can  be  worked  by  the  fingers  to  operate 
the  vertical  rudder,  while  the  main  portion  of 
the  lever  is  pushed  forward  or  backward  to 
warp  the  wings. 

In  the  European  Wright  machine  a  tail  was 
soon  added,  because  it  was  found  that  the  ma- 
chine pitched  markedly  in  flight.  This  pitching 
was  corrected,  to  be  sure,  by  manipulation  of 
the  horizontal  rudder,  but  this  required  con- 
siderable skill  on  the  pilot's  part.  Hence  a 
horizontal  surface  was  placed  in  the  rear  to  act 
as  a  steadying  tail,  which  surface  could  be 
turned  up  and  down  to  aid  the  elevation  rudder 
in  its  action.  In  the  American  machines,  made 
by  the  Wrights  themselves,  this  horizontal  tail 
has  also  been  incorporated  (Fig.  80).  What 
is  more,  the  front  horizontal  rudders  have  been 
abandoned  altogether  and  the  rear  horizontal 
surface  or  tail  employed  both  as  an  elevator  and 
a  steadying  surface.  The  result  has  been  that  the 
machine  flies  far  more  steadily  than  formerly. 


SOME   TYPICAL   BIPLANES     213 

The  earlier  Wright  machines  were  mounted 
on  skids.  The  machines  were  launched  on  a 
starting  rail  (Fig.  12)  in  the  manner  described 
in  Chapter  IV.  The  European  manufacturers 
of  Wright  machines  soon  introduced  wheels  on 
which  the  machine  ran  in  the  usual  manner,  the 
skids  serving  for  alighting  as  before.  This  im- 
provement has  been  adopted  by  the  Wrights 
(Fig.  14). 

The  motors  which  drive  the  American 
Wright  machines  are  made  by  the  Wrights 
themselves.  The  horse-power,  except  in  small 
racers,  varies  from  25  to  30,  which  is  consider- 
ably below  that  of  most  European  biplanes. 
The  motor  drives  two  propellers  revolving  in 
opposite  directions  at  the  rate  of  400  revolu- 
tions a  minute,  which  is  remarkably  slow  as 
propeller  speeds  go. 

The  Wright  racing  aeroplane,  which  made 
its  first  appearance  at  the  Belmont  Par!:  Inter- 
national Aviation  Meet  of  1910,  is  not  essen- 
tially different  from  the  regular  Wright  biplane. 
In  order  to  attain  high  speed,  the  planes  have 
been  reduced  in  spread,  and  consequently  in 
area,  and  a  V-motor  of  high  power  has  been  in- 


2i4    THE    NEW   ART   OF    FLYING 

stalled.  The  planes  are  21  feet  in  length  and 
3l/2  feet  wide.  The  combined  area  of  both 
planes  is  180  square  feet.  It  is  stated  that  the 
motor  develops  about  60  horse-power.  The 
machine  was  used  by  Johnstone  when  he  made 
an  altitude  flight  of  9,714  feet.  The  machine 
is  credited  with  a  speed  of  685^  miles  an  hour. 

THE  CURTISS  BIPLANE 

Like  the  Wrights,  Mr.  Glenn  H.  Curtiss 
has  departed  somewhat  from  the  type  that  he 
originally  evolved.  In  his  earlier  machines 
(Fig.  25)  the  supporting  planes  consisted  of 
"  rubberized "  silk  stretched  over  the  top  of 
a  light  spruce  frame.  The  spread  of  the  planes 
was  26.42  feet,  the  depth  4.5  feet,  the  dis- 
tance between  the  planes  5  feet,  and  the  area 
220  square  feet.  In  the  more  recent  machines 
the  spread  is  32  feet,  the  depth  5  feet,  and 
the  area  316  square  feet. 

The  horizontal  or  elevation  rudder  of  the 
Curtiss  biplane  consists  of  two  parallel  hori- 
zontal surfaces  mounted  in  front  of  the  ma- 
chine and  moved  in  unison  by  means  of  a  steer- 


.!  = 


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<U       t) 

rll 

"ij        (/3 

1-5 

o  ^^ 


a 


SOME   TYPICAL    BIPLANES     215 

ing-wheel.  A  long  bamboo  rod  connects  the 
horizontal  rudder  with  the  steering-wheel,  the 
arrangement  being  such  that  by  pushing  or  pull- 
ing the  steering-wheel  backward  or  forward,  the 
rudder  is  respectively  turned  down  or  up. 

The  vertical  rudder  of  the  Curtiss  machine 
is  a  single  surface  placed  in  the  rear  and  also 
operated  by  the  steering-wheel  through  the 
medium  of  cables.  To  work  the  vertical  rud- 
der the  steering-wheel  is  rocked  like  the  pilot- 
wheel  of  a  steamboat.  To  secure  steadiness 
in  flight  and  to  reduce  the  pitching  effect  a  hori- 
zontal surface  or  tail  is  mounted  in  the  rear. 

Side  to  side  balance  was  maintained  in  the 
Curtiss  machine  up  to  1910  by  means  of  two 
balancing  planes  of  about  12  square  feet  in 
area,  mounted  between  the  two  main  planes. 
These  balancing  planes  were  swung  in  opposite 
directions  by  cables  connected  with  a  yoke 
partially  surrounding  the  aviator's  body  and 
mounted  to  rock.  By  leaning  from  side  to  side 
the  aviator  moved  the  yoke  and  consequently 
the  balancing-planes.  The  arrangement  was 
such  that  the  instinctive  motion  of  the  body 
swung  the  balancing-planes. 


216    THE    NEW   ART   OF    FLYING 

In  the  late  Curtiss  machines  ailerons  (Fig. 
29)  similar  to  those  of  the  Farman  biplane 
(q.  v.)  are  employed.  They  are  operated  in 
the  same  manner  as  the  old  balancing-planes. 

The  motors  which  drive  the  machine  are 
made  by  Mr.  Curtiss  himself.  On  the  larger 
machines  the  motors  are  of  the  well-known 
V-type  and  develop  50  horse-power.  On  the 
smaller  machines  25  horse-power  vertical  cylin- 
der motors  are  used.  The  engine  is  controlled 
by  an  accelerator  pedal  on  the  left  of  the  steer- 
ing column.  There  is  also  a  throttle  lever  close 
to  the  pilot's  seat.  Another  pedal  under  the 
action  of  the  pilot's  right  foot  is  employed  to 
cut  off  the  ignition  and  to  apply  a  brake  to  the 
front  wheel  of  the  chassis  by  which  the  machine 
is  carried  on  the  ground.  Mr.  Curtiss  himself 
has  driven  machines  with  100  horse-power 
motors. 

The  propellers  are  made  of  wood  and  are 
two-bladed.  Their  diameter  is  6  feet,  the 
pitch  5  feet,  and  the  speed  1,200  revolutions 
a  minute. 

The  machine  starts  and  alights  on  three 
rubber-tired  wheels. 


SOME    TYPICAL    BIPLANES     217 

For  the  Belmont  Park  aviation  meeting  of 
1910  Mr.  Curtiss  made  a  machine  which  was 
practically  a  monoplane.  The  upper  plane  was 
reduced  to  a  surface  of  almost  negligible  area. 
At  the  meeting  in  question  the  machine  was 
not  given  a  very  extensive  trial,  so  that  it  could 
not  be  compared  with  the  Bleriot  and  other 
machines  that  were  entered. 

THE  FARMAN  BIPLANE 

The  Farman  biplane  is  the  outcome  of  Henry 
Farman's  experience  •  with  the  old,  cellular 
Voisin  biplanes  (Fig.  34).  Like  Curtiss,  he 
was  manifestly  influenced  by  the  Wrights,  as, 
indeed,  was  every  French  maker  of  flying- 
machines  after  the  memorable  flights  of  Wilbur 
Wright  in  France  in  1908.  As  it  now  stands, 
the  Farman  is  probably  the  most  widely  used 
biplane  in  Europe  and  deservedly  so  by  reason 
of  its  ingenious  and  extraordinarily  staunch 
construction. 

The  main  supporting  surfaces  of  the  Farman 
biplane  are  made  of  what  is  known  as  "  Conti- 
nental "  cloth,  a  special  fabric  manufactured 
for  aeronautic  purposes.  The  cloth  is  stretched 


218    THE    NEW   ART   OF    FLYING 

over  ribs  of  ash.  Although  the  dimensions 
vary  somewhat,  the  average  Farman  biplane 
has  a  spread  of  33  feet,  a  depth  of  6.6  feet, 
and  a  total  area  of  430  square  feet.  In  the 
later  machine  the  upper  plane  has  a  greater 
spread  than  the  lower.  The  planes  are  sepa- 
rated by  a  distance  of  7  feet. 

The  elevation  or  horizontal  rudder  is  car- 
ried out  in  front  of  the  machine,  after  the  early 
Wright  fashion.  Wires  run  from  the  rudder 
to  a  lever  held  by  the  pilot's  right  hand  (Fig. 
28).  By  pushing  the  lever  away  from  him, 
the  pilot  depresses  the  rudder;  by  pulling 
the  lever  toward  him,  he  tilts  the  rudder 
up. 

The  same  lever  controls  the  lateral  balance 
of  the  machine.  Four  hinged  flaps,  constitut- 
ing the  rear  corners  of  the  main  planes,  are 
connected  by  cables  with  the  lever.  By  throw- 
ing the  lever  from  side  to  side  the  flaps  (aile- 
rons) on  one  side  are  pulled  down,  and  the 
flaps  on  the  other  side  are  relaxed  so  that 
they  lie  practically  flush  with  the  main  planes. 
When  the  machine  is  standing  still  on  the 
ground,  the  flaps  hang  down.  As  soon  as  the 


SOME    TYPICAL    BIPLANES     219 

machine  is  in  flight,  they  stream  out  behind  the 
main  planes. 

The  vertical  rudder  consists  of  two  parallel 
vertical  surfaces  in  the  rear  of  the  machine, 
which  surfaces  are  connected  by  means  of  tiller 
cables  with  a  lever  worked  by  the  pilot's 
feet. 

Somewhat  in  advance  of  the  vertical  rudder 
are  two  horizontal  surfaces  which  constitute  a 
steadying  tail.  The  top  surface  of  this  tail  can 
be  swung  up  and  down  in  conjunction  with  the 
front  horizontal  rudder. 

The  motors  used  on  the  Farman  machine  are 
usually  Gnome  rotary  motors  of  50  horse- 
power, although  100  horse-power  motors  have 
been  used  on  occasion.  The  propeller  is  a 
Chauviere  wooden  propeller  of  two  blades,  with 
a  speed  of  1,200  revolutions  a  minute.  The 
pitch  of  the  propeller  is  4.62  feet,  the  diameter 
8.5  feet. 

The  machine  is  mounted  on  two  skids,  each 
of  which  is  fitted  with  a  pair  of  wheels.  Heavy 
elastic  bands  connect  the  skids  with  the  axles 
of  the  two  wheels.  In  alighting  the  bands  yield 
and  allow  the  skids  to  take  the  main  shock. 


220    THE    NEW   ART    OF    FLYING 

This  is  a  most  ingenious,  efficient,  and  simple 
invention,  which  has  been  widely  copied. 

THE  SOMMER  BIPLANE 

The  biplane  built  by  Farman's  former  pupil 
Roger  Sommer  (Fig.  83)  follows  the  Farman 
type  rather  closely.  The  supporting  surfaces 
consist  of  rubber  cloth  stretched  over  wooden 
ribs.  The  spread  is  33  feet,  the  depth,  5.2  feet, 
and  the  total  area  326  feet. 

The  horizontal  rudder  is  carried  well  out  in 
front  of  the  machine.  It  consists  of  a  single 
horizontal  surface.  As  in  the  Farman  machine, 
it  is  controlled  by  a  single  lever,  which,  instead 
of  being  placed  at  the  right,  is  mounted  at  the 
left.  The  operation  of  this  lever  and  the  con- 
sequent elevation  and  depression  of  the  rudder 
are  exactly  the  same  as  in  the  Farman  machine. 

As  in  the  Farman  machine,  ailerons  are  em- 
ployed to  maintain  side-to-side  balance.  These 
ailerons  are  to  be  found  either  on  both  planes 
or  only  on  the  upper  plane.  They  are  not  oper- 
ated, as  in  the  Farman  machine,  by  the  lever 
which  controls  the  horizontal  rudder.  Instead, 
the  Curtiss  principle  of  using  the  instinctive 


SOME    TYPICAL    BIPLANES     221 

movements  of  the  pilot's  body  is  adopted. 
Wires  leading  from  the  ailerons  are  attached 
to  a  yoke  partially  surrounding  the  aviator's 
body.  In  obedience  to  the  movements  of  the 
body  the  ailerons  are  pulled  down  and  up 
respectively. 

The  vertical  rudder  is  a  single  surface  at  the 
rear  of  the  machine  operated,  as  in  the  Farman 
machine,  by  a  foot  lever. 

To  steady  the  machine  a  single  horizontal 
surface  is  mounted  in  the  rear.  This  surface 
is  movable,  not  for  the  purpose  of  acting  as  an 
elevation  rudder,  but  to  increase  or  decrease  the 
stabilising  effect.  A  lever  at  the  aviator's  right 
controls  this  tail. 

The  machine  is  mounted  on  skids  and  wheels, 
the  skids  serving  for  alighting.  Rubber  springs 
are  employed  in  connection  with  the  wheels,  as 
in  the  Farman  machine. 

As  a  general  rule  Sommer  machines  are 
driven  by  50  horse-power  Gnome  motors,  which 
turn  a  two-bladed  Chauviere  propeller  at  the 
rate  of  1,200  revolutions  a  minute.  Some  ma- 
chines have  been  fitted  with  100  horse-power 
motors. 


CHAPTER    XIII 

SOME  TYPICAL   MONOPLANES 

MONOPLANES  differ  less  from  one  another 
than  biplanes.  Nearly  all  of  them  have  the 
same  system  of  lateral  control,  and  the  same 
method  of  mounting  the  motor.  As  a  general 
rule  this  system  of  lateral  control  is  the  Wright 
wing-warping  method.  The  motors  are  usu- 
ally Gnome  motors  mounted  in  front  of  the 
machines. 

THE  ANTOINETTE  MONOPLANE 

Antoinette  monoplanes  (Fig.  84)  are  de- 
signed and  built  by  Levavasseur,  a  well-known 
manufacturer  of  motors. 

The  single  silk  surface  of  an  Antoinette  mon- 
oplane is  constructed  in  two  halves  which  are 
so  mounted  that  they  form  a  slight  dihedral 
angle.  This  plane  is  braced  to  a  central  mast 
or  spar,  and  is  carried  on  a  girder-like  frame 
of  aluminium,  cedar,  and  ash.  The  spread  of 
the  plane  is  49  feet ;  the  area  405  square  feet. 


SOME  TYPICAL  MONOPLANES     223 

The  horizontal  rudder  is  a  single  surface  at 
the  extreme  rear  of  the  machine  and  is  con- 
trolled by  a  hand-wheel  at  the  aviator's  right 

(Fig.  32). 

The  vertical  rudder  comprises  two  surfaces 
at  the  rear  of  the  machine.  Tiller  cables  lead 
from  the  surfaces  to  a  lever  operated  by  the 
aviator's  feet. 

To  balance  the  machine  from  side  to  side  the 
plane  is  warped  after  the  Wright  principle.  In 
contradistinction  to  the  Wright  machine,  how- 
ever, the  front  edges  are  flexible  and  the  rear 
edges  fixed.  To  warp  the  plane  a  hand-wheel 
is  provided  at  the  aviator's  left. 

The  mast,  to  which  the  plane-halves  are 
braced,  contains  a  pneumatic  shock-absorber  in 
its  lower  end,  besides  which  there  are  two 
wheels  with  heavy  pneumatic  tires  and  a  for- 
ward plough-like  skid.  A  skid  in  the  rear  is 
used  to  support  the  tail. 

On  each  side  of  the  body  is  a  horizontal,  fan- 
shaped  keel  at  the  rear  to  steady  the  machine 
longitudinally.  A  vertical  fin  above  this  hori- 
zontal fin  gives  a  certain  amount  of  lateral 
stability. 


224    THE    NEW   ART   OF    FLYING 

An  8-cylinder  V-type  water-cooled  Antoinette 
motor  of  50  horse-power  is  placed  in  front  of 
the  machine  and  drives  a  y-foot  propeller.  At 
the  International  Aviation  Meeting  held  in 
1910  at  Belmont  Park,  Latham  flew  a  100 
horse-power  Antoinette. 

The  Antoinette  monoplanes  which  are  built 
in  Germany  are  equipped  with  100  horse-power 
Gnome  motors  of  fourteen  cylinders.  The  area 
of  the  wings  can  be  reduced  by  about  one  square 
metre,  the  smaller  area  being  employed  when 
the  aviator  is  flying  alone.  When  three  pas- 
sengers are  carried  besides  the  aviator,  the 
span  can  be  increased  to  fifteen  metres,  so  that 
the  area  amounts  to  four  square  metres.  The 
passengers  are  placed  symmetrically,  so  that 
the  centre  of  gravity  of  the  machine  is  not  dis- 
turbed. This  large  Antoinette  machine  is  some- 
what longer  than  the  normal  Antoinette,  built 
in  France.  Since  the  utilisation  of  the  Gnome 
motor  means  the  abandonment  of  the  usual 
Antoinette  water-cooling  plant,  and  such  auxil- 
iary apparatus  as  radiators,  pumps,  etc.,  it  was 
necessary  to  redistribute  the  weight.  Accord- 
ingly the  German  machine  is  longer  than  the 


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SOME  TYPICAL  MONOPLANES     225 

French,  so  that  the  motor  can  be  placed  out 
further. 

THE  BLERIOT  MONOPLANES 

Louis  Bleriot  is  a  well-to-do  manufacturer 
of  automobile  lamps  whose  attention  was  di- 
rected to  flying-machines  in  1906.  He  has  the 
distinction  of  having  broken  more  machines 
and  more  frequently  risked  his  life  than  any 
other  man  interested  in  the  new  sport.  What 
is  more,  he  was  the  first  man  who  ever  flew  a 
monoplane. 

Bleriot's  remarkable  experience  has  resulted 
in  the  development  of  two  types  of  machines 
known  respectively  as  the  Bleriot  XI  (Fig.  81) 
and  the  Bleriot  XII  (Fig.  88).  The  Bleriot 
XI  is  a  fast  model  patterned  after  that  with 
which  Bleriot  flew  across  the  English  Channel; 
the  Bleriot  XII  is  a  passenger-carrying  machine, 
which  differs  somewhat  from  the  XI. 

The  main  plane  of  the  No.  XI  is  built  in 
halves  and  consists  of  "  Continental  rubber  " 
stretched  over  a  wooden  frame.  In  order  that 
the  machine  may  be  readily  transported  the 
halves  of  the  plane  can  be  detached  from  a 


226    THE    NEW   ART   OF    FLYING 

central  joint.  This  detachability,  moreover, 
renders  it  possible  to  interchange  wings  of  large 
and  small  area.  The  spread  is  normally  28.2 
feet,  the  depth  6.5  feet,  and  the  total  area  151 
square  feet. 

To  steady  the  machine  longitudinally  in  flight 
a  horizontal  surface  or  tail  is  employed.  The 
horizontal  or  elevation  rudder  consists  of  two 
movable  surfaces,  one  at  each  side  of  this  tail. 
The  horizontal  rudder  is  operated  by  a  central 
lever  in  the  manner  described  in  Chapter  V. 

The  vertical  rudder  of  the  Bleriot  XI  con- 
sists of  a  vertical  surface  in  the  rear  of  the 
machine.  It  is  operated  by  tiller  wires  con- 
nected with  a  foot  lever. 

Lateral  control  of  the  machine  is  obtained 
by  wing-warping,  as  in  the  Wright  biplane, 
For  this  purpose  the  central  lever  or  bell- 
column,  described  in  Chapter  V,  is  employed, 
the  column  being  thrown  from  side  to  side  to 
pull  on  one  wing-warping  wire  and  to  slacken 
the  other. 

In  the  machine  with  which  he  flew  across 
the  English  Channel,  Bleriot  used  a  25  horse- 
power Anzani  motor.  Since  then  50  horse- 


SOME  TYPICAL  MONOPLANES     227 

power  Gnome  motors  have  usually  been  em- 
ployed, the  motor  being  mounted  in  front  of 
the  machine  and  driving  a  two-bladed  Chau- 
viere  propeller  6.87  feet  in  diameter  at  the 
rate  of  1,200  to  1,400  revolutions  a  minute. 

The  starting  and  alighting  gear  of  the  Ble- 
riot  XI  consists  of  rubber-tired  wheels  and 
rubber  shock-absorbers.  For  the  rear  wheel,  as 
shown  in  Fig.  86,  a  skid  has  been  substituted. 

In  the  smaller  type  of  Bleriot  a  fuel  tank  is 
placed  very  far  below  the  frame  in  order  to 
lower  the  centre  of  gravity.  In  the  larger  type 
two  fuel  tanks  are  placed  between  the  wings 
in  the  body  of  the  machine  right  in  front  of  the 
pilot's  seat.  In  order  that  the  lowered  fuel 
tank  of  the  small  Bleriot  XI  may  offer  as  little 
resistance  to  the  air  as  possible,  it  is  given  a 
fish  form  (Fig.  86)  for  the  reason  that  Prandtl 
has  proven  that  such  shapes  offer  the  least 
resistance. 

Racing  machines  are  also  made  on  the  lines 
of  the  Bleriot  XI,  but  with  a  smaller  wing- 
spread  and  100  horse-power,  fourteen-cylinder 
Gnome  motors. 

The  passenger-carrying  Bleriot  XII  is  so  con- 


228    THE    NEW   ART   OF    FLYING 

structed  that  the  aviator  sits  with  his  passen- 
gers under  the  main  plane,  back  of  the  motor. 
This  type  is  now  practically  abandoned.  In 
the  Bleriot  XI  he  sits  with  his  body  above  the 
main  plane.  A  later  passenger-carrying  model 
has  been  evolved  in  which  the  two  occupants 
of  the  machine  sit  side  by  side  above  the  plane, 
as  in  the  regular  Bleriot  XL 

Early  in  1911  Bleriot  brought  out  a  remark- 
able 10  passenger  monoplane,  the  lateral  sta- 
bility of  which  was  controlled  by  ailerons  and 
the  100  horse-power  motor  of  which  was  placed 
with  the  propeller  directly  behind  the  plane, 
following  Maxim's  suggestion.  A  front  hori- 
zontal rudder  was  also  provided,  similar  to 
that  of  the  Farman  biplane. 

THE  SANTOS-DUMONT  MONOPLANE 

By  far  the  smallest  flying-machine  of  the  day 
is  the  monoplane  designed  by  Santos-Dumont. 
Because  of  its  littleness  it  is  extremely  fast. 

The  supporting  surface  consists  of  silk 
stretched  over  bamboo  ribs.  This  silken  sur- 
face is  braced  by  wires  to  a  central  frame  of 
bamboo  and  metal  tubing.  The  spread  is  18 


SOME  TYPICAL  MONOPLANES     229 

feet,  the  depth  6.56  feet,  and  the  area  113 
square  feet. 

The  vertical  rudder  and  the  horizontal  rud- 
der, usually  entirely  distinct,  in  most  biplanes 
and  monoplanes,  are  here  combined  after  the 
Langley  principle.  This  combined  rudder  is 
carried  on  a  universal  joint  so  that  it  can  be 
turned  in  any  direction.  Although  they  are 
mounted  together,  the  horizontal  and  vertical 
members  of  the  rudder  are  operated  indepen- 
dently. The  vertical  surface  is  controlled  by 
a  hand-wheel  or  lever  at  the  pilot's  left  hand. 
The  horizontal  rudder  is  operated  by  a  lever 
held  in  the  aviator's  right  hand. 

Following  the  principle  of  Curtiss,  lateral 
control  is  effected  by  the  instinctive  movements 
of  the  aviator's  body;  but  instead  of  employ- 
ing balancing  planes  or  ailerons  Santos-Dumont 
warps  the  plane.  The  wires  leading  from  the 
plane  are  connected  with  a  steel  member  sewed 
on  the  pilot's  coat.  Hence  the  pilot  has 
only  to  sway  his  body  in  order  to  warp  the 
wings. 

The  starting  and  alighting  gear  consists  of 
two  wheels  at  the  front  and  a  skid  at  the  rear. 


230    THE    NEW   ART   OF    FLYING 

No  tails  or  other  stabilising  surfaces  are 
used,  although  the  horizontal  member  of  the 
rudder  undoubtedly  acts  as  a  tail,  as  in  the  newer 
Wright  biplane. 

The  motor  may  be  of  any  type.  Darracq, 
Clement-Bayard,  and  Panhard  motors  of  30 
horse-power  have  been  used.  The  propeller  is 
a  two-bladed  Chauviere. 


CHAPTER   XIV 

THE  FLYING-MACHINE  OF  THE  FUTURE 

WHAT  will  the  flying-machine  of  the  future  be 
like?  He  would  be  a  wise  man  indeed  who 
could  predict  with  any  degree  of  accuracy  the 
exact  form  and  dimensions  of  the  coming  aero- 
plane. The  dreams  of  the  old-time  imaginative 
novelist  seem  almost  to  be  realised  now.  Our 
more  modern  Kipling,  looking  back  in  his 
mind's  eye  at  our  feeble  efforts,  talks  with  scorn 
in  the  "  Night  Mail  "  of  "  the  days  when  men 
flew  wooden  kites  over  oil-engines."  Yet  it  is 
not  likely  that  we  shall  graduate  from  that 
crude  type  for  many  years  to  come.  A  scien- 
tific forecast  of  the  flying-machine's  possibili- 
ties and  its  effect  on  human  affairs  must 
therefore  be  deduced  from  present  aeroplane 
facts. 

The  aeroplane  of  our  time  is  a  thing  of 
almost  feathery  lightness.  In  its  construction 
the  lightest  and  toughest  woods  and  the  small- 
est possible  amount  of  metal  must  be  used.  As 


23  2     THE    NEW    ART    OF    FLYING 

a  result,  it  is  wellnigh  as  delicate  as  a  watch, 
and  like  a  watch  it  must  be  handled  with  some 
care.  Since  the  motor  is  the  heaviest  part  of 
a  flying-machine,  it  offers  the  most  serious  ob- 
stacle to  the  attainment  of  lightness.  Because 
of  the  motor's  necessarily  small  size  its  power 
is  none  too  generous,  and  because  of  its  delicate 
construction  it  breaks  down  with  awkward 
ease.  Hence  it  is  safe  to  prophesy  that  the 
flying-machine  of  the  future  will  be  equipped 
with  motors  far  higher  in  power  than  those  at 
present  in  use. 

It  is  probable  that  the  future  aeroplane  will 
carry  two  motors,  instead  of  one,  each  motor 
independently  operative,  so  that  if  one  fails, 
the  other  will  still  be  able  to  drive  the  machine 
safely  through  the  air.  For  military  purposes 
at  least,  such  a  double-motor  aeroplane  is  abso- 
lutely necessary.  Imagine  a  spy  in  the  air 
compelled  to  glide  ignominiously  down  in  an 
enemy's  camp,  because  his  engine  failed  him! 
Mere  considerations  of  safety  demand  the  in- 
stallation of  two  motors  on  a  flying-machine. 
In  March,  1910,  the  French  aviator  Crochon 
fell  to  the  ground  in  a  cross-country  flight  from 


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THE  FUTURE  FLYING-MACHINE    233 

Mourmelon  to  Chalons,  because  his  motor 
broke  down.  Le  Blon  was  killed  at  San  Sebas- 
tian on  April  2,  1910,  as  a  result  of  a  similar 
motor  trouble.  During  the  Nice  meeting  in 
April,  1910,  Chavez  and  Latham  mercifully 
dropped  into  the  Mediterranean,  also  because 
of  motor  trouble.  All  of  these  accidents  might 
have  been  avoided  if  the  aviators  could  have 
relied  upon  a  second  motor. 

The  aviator  of  the  present  day  is  somewhat 
in  the  position  of  a  bicycle  rider  on  a  slack  wire, 
armed  with  a  parasol.  He  must  exercise  inces- 
sant vigilance,  lest  he  lose  his  balance.  The 
strain  upon  nerves  and  muscles,  for  the  begin- 
ner at  least,  is  tremendous.  Hence,  even  now, 
we  hear  of  automatic  devices  which  will  prevent 
the  loss  of  a  flying-machine's  equilibrium  and 
which  will  enable  the  aviator  to  soar  in  the  sky 
more  blithely  than  he  can  at  present. 

Balloonists  find  difficulty  in  ascertaining  their 
location,  particularly  after  descending  from  a 
cloud  bank.  It  is  true  that  the  aviator  can 
swoop  down  to  the  earth  and  find  out  where  he 
is.  Nevertheless,  it  is  very  likely  that  in  the 
future  he  will  be  provided  with  charts  and  in- 


234    THE    NEW   ART    OF    FLYING 

struments  which  will  obviate  that  necessity,  — 
charts  which  will  indicate  landmarks  and  instru- 
ments which  will  indicate  the  angle  of  the  flight 
path  and  which  will  include  convenient  field 
glasses  and  day  and  night  signalling  devices. 
Needless  to  say  the  aviator  will  carry  a  com- 
pass, probably  a  prismatic  compass  from  which 
directions  can  be  taken  with  great  accuracy  so 
long  as  fixed  objects  on  the  earth  are  visible. 
No  doubt  the  compass  will  have  a  dial  covered 
with  luminous  material,  visible  in  the  dark. 
At  night  a  trailing-line  will  be  cast  overboard, 
fitted  with  some  electrical  indicator,  which  will 
ring  a  bell  if  some  object  should  be  struck,  to 
warn  the  pilot  that  he  is  flying  too  low.  The 
German  Aerial  Navy  League  has  proposed 
that  special  beacon  lights  be  erected  at  certain 
points.  The  aviator  of  the  future  will  certainly 
need  some  such  guidance  if  he  flies  by  night,  — 
some  light  which  will  send  a  long  beam  in  the 
direction  in  which  the  wind  is  blowing. 

Two  men  at  least  will  be  carried  by  the  aero- 
plane of  the  future,  —  one  to  look  after  the 
controlling  mechanism  and  the  other  to  navi- 
gate. The  military  aeroplane  will  surely  be  so 


THE  FUTURE  FLYING-MACHINE    235 

manned;    for  one  man  alone  cannot  perform 
the  duties  of  mechanician  and  observer. 

Explorations  into  unknown  lands  will  be 
robbed  of  their  perils  by  the  flying-machine. 
The  hummocks  of  the  Arctics,  the  jungles  of 
Africa,  the  morasses  of  a  country  untrodden  by 
the  foot  of  man  can  hide  nothing  from  the  ex- 
ploring aviator.  Tasks  which  formerly  occu- 
pied years  for  -their  achievement  will  hence- 
forth be  accomplished  in  as  many  months, 
weeks,  or  even  days.  If  Lieutenant  Shackleton 
found  the  motor-car  of  service  in  Antarctic  ex- 
ploration, what  shall  be  said  of  the  flying-ma- 
chine which  speeds  on  its  journey  unimpeded  by 
mountains  of  snow  or  grinding  pack-ice?  The 
character  of  the  information  gathered  by  the 
future  explorer-aviator  will  be  of  greater  scien- 
tific value  than  that  which  is  at  present  so  pain- 
fully collected.  A  Livingstone  or  a  Stanley  chop- 
ping his  way  through  dense  tropical  vegetation 
brings  back  no  complete  map  of  the  region  trav- 
ersed. All  that  he  can  show  is  his  itinerary,  — 
a  mere  fringe  of  the  new  country.  Mountains 
and  rivers  he  indicates  rather  than  charts.  In- 
stead of  crawling  over  the  face  of  our  planet, 


236    THE    NEW   ART    OF    FLYING 

the  sky-explorer  will  some  day  survey  it  from 
a  height.  He  will  see  his  Africa  or  Asia  or 
India  spread  before  him  like  a  map.  His  eye 
will  sweep  an  area  measuring  hundreds  of 
square  miles  in  extent.  The  camera  will  record 
those  topographical  peculiarities  which  he  came 
to  note,  and  he  will  be  spared  the  necessity  of 
imperilling  his  life  to  discover  the  source  of  a 
river  or  the  secret  of  some  Tibetan  Forbidden 
Kingdom. 

So  far  as  actual  appearance  goes,  the  opin- 
ions of  present-day  flying  experts  differ  as  to  the 
flying-machine  of  the  future.  Mr.  R.  W.  A. 
Brewer,  an  English  authority,  sees  a  larger  and 
a  heavier  machine  than  we  have  at  present,  a 
kind  of  air  yacht,  weighing  at  least  three  tons, 
and  built  with  a  boat-body.  The  craft  of  his 
fancy  will  be  decked  in.  It  will  carry  several 
persons  conveniently  and  will  be  provided  with 
living  and  sleeping  accommodations.  He  proph- 
esies that  it  will  fly  at  speeds  of  one  hundred  and 
fifty  to  two  hundred  miles  an  hour,  for  the  rea- 
son that  high  speeds  in  flying,  according  to  some 
authorities,  mean  less  expenditure  of  power  than 
lower  speeds.  Mr.  F.  W.  Lanchester,  as  we 


00 

tj) 


THE  FUTURE  FLYING-MACHINE    237 

have  pointed  out  in  a  previous  chapter,  enter- 
tains similar  views  on  the  necessity  of  high 
speed.  If  it  is  ever  possible  for  an  aeroplane 
to  travel  at  such  terrific  velocities,  whole  conti- 
nents will  become  the  playgrounds  of  aviators. 
Daily  trips  of  one  thousand  miles  would  not 
be  extraordinary.  It  is  even  conceivable  that 
there  will  be  aeroplane  liners  which  will  travel 
from  Europe  to  America  in  twenty-four  hours. 

It  seems  certain  that  special  starting  and 
alighting  grounds  will  be  ultimately  provided 
throughout  the  world.  If  tramcars  must  have 
their  stables  and  their  yards,  it  is  not  unreason- 
able to  demand  the  provision  of  suitable  aero- 
plane stations.  Depots  or  towers  will  be  erected 
for  the  storage  of  fuel  and  oil,  —  garages  on 
stilts,  in  a  word.  The  aviator  in  need  of  sup- 
plies will  signal  his  wants,  lower  a  trailing  line 
and  pick  up  gasoline  by  some  such  device  as 
we  now  employ  to  catch  mail  sacks  on  express 
trains. 

It  may  well  be  that  the  advent  of  the  flying- 
machine  will  have  a  marked  effect  on  our  archi- 
tecture. Some  day  houses  will  be  provided  with 
landing  stages,  assuming  that  the  aeroplane 


238     THE    NEW   ART    OF    FLYING 

will  be  able  to  alight  more  easily  than  at  pres- 
ent and  without  the  necessity  of  running  along 
the  ground  for  some  distance  before  it  expends 
its  momentum.  Ely's  remarkable  feat  in  land- 
ing on  the  deck  of  a  warship  in  the  harbour  of 
San  Francisco  shows  that  the  thing  is  not  re- 
motely possible.  When  that  day  dawns,  roofs 
will  disappear  in  favour  of  flat  terraces  suited 
for  launching  and  landing.  A  business  man  in- 
stead of  travelling  in  a  lift  from  the  ground 
floor  of  a  building  to  his  office  on  the  twenty- 
first  floor,  will  start  from  the  roof  of  the  build- 
ing and  proceed  downward. 

Above  all  things,  flyirg  must  be  safer  than 
it  is  now.  Although  the  dangers  of  a  sport 
will  inevitably  attract  to  it  adventurous  spirits, 
a  really  commercial  machine  must  satisfy  the 
requirements  of  the  highly  nervous  man  or 
woman  to  whom  sailing  a  yacht  seems  a  suicidal 
pastime. 

The  early  days  dl  the  bicycle  and  the  auto- 
mobile industries  offer  a  close  parallel  to  the 
present  position  of  the  aeroplane  industry. 
The  pioneers  having  shown  the  way,  the  ma- 
chine immediately  became  an  instrument  of 


THE  FUTURE  FLYING-MACHINE    239 

sport.  Speed  was  the  thing  first  desired,  and 
the  speed  of  anything  that  moves  can  best  be 
demonstrated  in  a  competition.  Bicycle  and 
automobile  races  became  and  still  are,  to  some 
extent,  the  manufacturer's  opportunity  of  test- 
ing and  demonstrating  the  quality  of  his  ma- 
chines. Long  before  the  manufacture  of  either 
touring  bicycles  or  touring  automobiles  as- 
sumed their  present  proportions,  the  production 
of  the  racing  machine  was  all  important.  The 
flying-machine  is  now  in  this  stage.  Races  and 
endurance  tests  will  be  the  battles  from  which 
will  emerge  the  flying-machine  of  the  future,  — 
the  machine  capable  of  sustained  flights,  many 
hours  in  duration,  at  speeds  of  eighty  and  one 
hundred  miles  an  hour.  The  racer  will  give 
birth  to  the  touring  flyer,  just  as  the  touring  car 
of  to-day  was  evolved  from  the  racing  car  of 
five  years  ago. 

Incredible  as  it  may  seem,  in  less  than  a  year 
from  the  date  when  Blerioc  flew  over  the  Eng- 
lish Channel,  a  feat  which  set  France  aeroplane- 
mad,  the  actual  sales  of  flying-machines  out- 
numbered the  actual  sales  of  automobiles  in 
the  first  year  of  their  commercial  development. 


240    THE    NEW    ART    OF    FLYING 

A  flying  Frenchman  clamours  for  his  Bleriot 
or  Farman  as  impatiently  as  an  automobiling 
American  millionaire  for  his  high-powered  car, 
ordered  months  in  advance.  The  one  is  no 
more  inclined  to  bide  his  time  than  the  other. 
Hence  agents  have  sprung  up  in  Paris,  who 
order  machines  from  the  manufacturer  on  spec- 
ulation, and  receive  as  much  as  $500  to  $1,000 
above  the  factory  price  for  immediate  delivery. 
In  Paris  at  least  such  signs  as  "  Bouvard  et 
Pecuchet,  Agents  pour  Monoplanes  Antoi- 
nette "  can  be  seen  even  now,  —  the  harbinger 
of  a  great  industry  of  the  future  and  of  flying- 
machine  quarters  in  our  large  cities. 

Compared  with  the  flying-machine  of  the 
future,  the  motor-car  will  seem  as  tame  and  dull 
as  a  cart,  drawn  by  a  weary  nag  on  a  dusty 
country  road.  Confined  to  no  route  in  particu- 
lar, unhampered  by  speed  restrictions,  the  speed 
maniac  can  drink  his  fill  in  the  high-powered 
monoplane.  Even  the  most  leisurely  of  air- 
touring  machines  will  travel  at  speeds  that  only 
a  racing  automobile  now  attains,  while  the  air 
racer  will  flit  over  us,  a  mere  blur  to  the  eye 
a  buzz  to  the  ear.  In  an  hour  or  two  a 


Photograph  by  Edwin  Levick 

Fig.  83. — The  100  horsepower  Antoinette  monoplane 

that  Hubert  Latham  flew  at  Belmont  Park 

during  the  International  Aviation 

Tournament  of  1910 


THE  FUTURE  FLYING-MACHINE    241 

whole  province  will  be  traversed;  in  a  day  a 
whole  continent.  An  air  tourist,  a  few  years 
hence,  will  breakfast  in  Paris  and  sup  the  same 
evening  in  Moscow.  His  air-charts,  the  equiva- 
lent of  our  present  road  automobile  maps  will  be 
an  atlas,  a  book  in  which  the  air-routes  of  all 
Europe  are  laid  down.  Swifter  than  any  storm 
will  be  his  flight.  If  the  black,  whirling  mael- 
strom of  a  cyclone  looms  up  before  him,  he  can 
make  a  detour  or  even  outspeed  it;  for  the 
velocity  of  his  machine  will  be  greater  than  that 
of  the  fiercest  of  howling,  wintry  blasts.  At  a 
gale  which  now  drives  every  aviator  timorously 
to  cover,  he  snaps  a  contemptuous  finger, 
plunges  through  it  in  a  breathless  dash  and 
emerges  again  in  the  sunshine,  as  indifferent  to 
his  experience  as  a  locomotive  engineer  after 
running  through  a  shower. 

The  aspect  of  the  heavens  will  be  wonder- 
fully changed  when  the  pleasure  plane  of  the 
air  has  arrived.  Black  specks  will  dot  the  blue 
sky,  more  like  birds  than  machines,  specks  that 
the  practised  will  recognise  as  impetuous  and 
daring  high  flyers.  Lower  down  the  less  reck- 
less will  perform  their  evolutions,  and  the  whirr 


242    THE   NEW   ART   OF    FLYING 

of  their  motors  will  be  as  the  droning  of  bees, 
so  numerous  will  they  be. 

All  this  deals  with  the  sport.  Has  the  aero- 
plane no  mercantile  future?  Shall  we  see 
flocks  of  gigantic  artificial  birds,  freighted  with 
heavy  cargoes,  darkening  the  sky  as  they  wing 
their  way  across  the  Atlantic  or  the  continent? 
Will  travelling  by  steamship  and  railway  give 
way  to  the  aeroplane? 

The  most  sanguine  aeronautic  engineer  would 
not  venture  to  predict  the  supplanting  of  the 
freight  train  or  the  steamer  by  the  aeroplane. 
For  many,  many  years  to  come  the  flying- 
machine  will  remain  what  it  is  now,  a  vehicle  of 
sport  and  war  only.  Perhaps  it  may  never  be 
anything  more.  Why?  Because  it  cannot  be 
made  big  enough.  The  carrying  capacity  of  an 
aeroplane  depends  on  its  spread  of  plane.  To 
increase  the  load  means  so  important  an  in- 
crease in  spread  that  an  unmanageable  area  of 
supporting  surface  would  be  necessary.  In 
order  to  secure  the  necessary  strength  to  uphold 
this  increased  area  an  increased  weight  per 
square  yard  is  entailed.  Hence  it  is  unlikely 
that  aeroplanes  carrying  many  passengers  will 


THE  FUTURE  FLYING-MACHINE    243 

be  built  in  our  time.  Not  so  very  long  ago  Mr. 
Orville  Wright  expressed  the  opinion  that  aero- 
planes "  will  never  take  the  place  of  trains  or 
steamships  for  the  carrying  of  passengers.  My 
brother  and  I  have  never  figured  on  building 
large  passenger-carrying  machines.  Our  idea 
has  been  to  get  one  that  would  carry  two,  three, 
or  five  passengers,  but  this  will  be  the  limit  of 
our  endeavours." 

The  late  Prof.  Samuel  P.  Langley  discovered 
in  the  course  of  his  classic  experiments  that  the 
higher  the  speed  at  which  a  plane  travels 
through  the  air  the  less  is  the  supporting  sur- 
face required.  Hence  there  is  a  chance  that  a 
machine  may  be  constructed  in  the  future  which, 
taking  advantage  of  this  law,  will  be  provided 
with  a  supporting  surface  adjustable  in  area, 
so  that  it  can  start  with  a  large  surface,  and 
fold  up  its  planes  at  full  speed.  In  such  a 
machine  the  supporting  surface  would  be  ulti- 
mately reduced  until  it  is  a  thin  edge.  We 
would  have  an  aeroplane  propelled  by  great 
power,  supported  largely  by  the  pressure  against 
its  body,  its  wings  reduced  to  mere  fins,  serving 
to  guide  its  motion. 


244    THE    NEW    ART    OF    FLYING 

As  a  future  commercial  possibility,  the  air- 
ship is  far  more  promising  than  the  aeroplane. 
To  the  size  of  the  airship  there  is  no  limit. 
Indeed,  the  larger  it  can  be  built  the  more  eco- 
nomically can  it  be  driven,  when  we  measure 
economy  by  ratio  of  carrying  power  to  cost  of 
operation.  Just  how  large  an  airship  can  be 
constructed  is  a  question  of  constructive  en- 
gineering. In  considering  that  question  the  late 
Prof.  Simon  Newcomb  pointed  out  that  econ- 
omy is  gained  only  when  the  dimensions  of  an 
airship  are  so  increased  that  it  will  carry  more 
than  an  ocean  steamer  or  a  railroad  train.  To 
attain  that  end  he  estimated  that  it  would  be 
necessary  to  build  an  airship  at  least  half  a  mile 
in  length  and  six  hundred  feet  in  diameter. 
Such  an  airship  might  carry  a  cargo  of  ten  thou- 
sand tons  or  fifteen  thousand  passengers.  The 
construction  of  so  huge  a  craft  is  not  an  utter 
engineering  absurdity,  remote  as  it  may  seem 
to  us  now.  We  recently  witnessed  something 
like  this  when  Count  von  Zeppelin's  passenger- 
carrying  airship  made  a  voyage  that  excited 
the  admiration  of  the  world,  even  though  the 
vessel  was  wrecked  in  a  storm.  Some  fourteen 


THE  FUTURE  FLYING-MACHINE    245 

passengers  were  transported  on  that  remark- 
able trip,  for  whom  adequate  seating  and  dining 
accommodations  were  provided.  But  the  cost 
of  operating  such  a  giant  of  the  air  is  enormous. 
After  all  is  said,  money  will  decide  the  ques- 
tion of  the  commercial  possibilities  of  flying- 
machines  and  airships.  How  much  does  it  cost 
to  build?  How  much  does  it  cost  to  maintain? 
How  much  does  it  cost  to  operate?  Not  until 
these  questions  are  answered  satisfactorily  can 
we  tell  whether  or  not  the  aeroplane  will  ever 
be  anything  more  than  a  racing  machine  for 
gilded  youth  and  the  dirigible  an  air-yacht  for 
bankers  too  old  for  the  more  perilous  aeroplane. 


CHAPTER    XV 

THE    LAW  OF   THE   AIR 

IT  is  one  of  the  most  difficult  tasks  of  govern- 
ment to  adapt  existing  laws  to  those  incessant 
changes  in  the  relationships  of  nations  and  in- 
dividuals which  are  brought  about  by  the  in- 
vention of  new  arts  and  industries.  The  rail- 
road, the  telegraph,  the  telephone,  and  wire- 
less signalling  have  each  given  the  legislatures 
of  the  world  no  little  concern  in  developing 
codes  which  would  enable  the  new  inventions 
to  take  their  place  in  our  daily  lives  without  too 
greatly  disturbing  vested  rights. 

Englishmen  and  Americans  are  fortunate  in 
having  a  common  law,  which,  although  based 
upon  custom  and  precedent,  is  nevertheless  so 
flexible  that  it  is  able  to  adapt  itself  to  the  new 
conditions  which  the  flying-machine  will  create. 
To  supplement  whatever  shortcomings  the  com- 
mon law  may  have,  there  can  be  no  doubt  that 
special  statutes  will  be  passed  in  this  country 
and  England  to  define  the  relations  of  the  air- 


THE   LAW   OF   THE   AIR       247 

men  to  people  on  the  earth  below.  European 
nations  develop  their  laws  more  consciously. 
They  even  anticipate  conditions  that  may  arise 
by  the  introduction  of  a  new  invention.  Thus 
we  find  that  continental  jurists  have  given  con- 
sideration to  questions  of  such  detail  as  the 
nationality  to  be  ascribed  to  persons  born  on 
board  voyaging  air-craft,  rights  in  respect  of 
salvage,  and  other  doctrines  drawn  from  mari- 
time law.  Twenty  years  hence  it  will  be  inter- 
esting to  compare  Anglo-Saxon  air-laws  evolved 
from  custom  and  actual  experience,  with  the  air- 
laws  of  the  continent,  many  of  them  enacted 
before  aerial  navigation  was  really  established. 
The  mere  fact  that  aeroplanes  and  airships 
plough  the  air  above  us  is  in  itself  a  circum- 
stance that  gives  rise  to  a  new  legal  situation. 
As  Professor  Meli  of  Zurich  has  put  it,  a  careful 
man  must  now  look  not  simply  in  front  of  him 
and  on  either  side,  but  above  him  as  well. 

Has  the  airman  any  inherent  right  to  navi- 
gate the  air  at  all?  That  is  the  first  question 
that  must  be  decided  by  civilised  countries, 
whether  they  be  Anglo-Saxon,  European,  or 
Asiatic.  The  question  of  an  inherent  right  must 


248    THE    NEW   ART   OF    FLYING 

be  considered  both  from  the  standpoint  of  the 
private  property  owner  and  from  the  standpoint 
of  international  law. 

Even  among  lawyers  the  old  saying  that  to 
the  owner  of  a  piece  of  land  belongs  not  only 
the  earth  beneath  his  feet  to  the  very  centre  of 
the  globe,  but  the  air  above  his  property  to  an 
infinite  height,  is  regarded  as  a  basic  principle 
of  the  English  common  law.  Yet,  to  use  the 
words  of  Brett,  Master  of  the  Rolls,  in  the  case 
of  Wandsworth  Board  of  Works  v.  United 
Telephone  Company,  (1884)  13  Q.  B.  D.  904, 
this  old  maxim  is  at  best  a  u  fanciful  phrase. " 
The  maxim  can  be  traced  to  Coke  upon  Littleton 
and  to  Blackstone.  In  all  the  vast  body  of  deci- 
sions on  which  the  English  common  law  is  based, 
there  can  be  found  none  in  which  the  ownership 
of  the  air  to  a  height  above  that  at  which  a  prop- 
erty owner  could  make  reasonable  use  of  it,  is 
the  point  at  issue.  It  is  true  that  Coke's  old 
saw  and  its  reiteration  by  Blackstone  have  been 
approved  in  many  a  dictum;  but  dicta  are  not 
decisions.  If  the  doctrine  were  really  good 
common  law,  every  man  who  sailed  over  the 
land  of  another  would  be  a  trespasser.  Sup- 


THE    LAW   OF   THE   AIR       249 

pose  that  an  action  were  brought  to  collect  dam- 
ages for  trespass.  It  is  hardly  likely  that  even 
nominal  damages  could  be  recovered,  for  the 
simple  reason  that  no  injury  has  been  worked 
to  the  landowner's  estate  and  no  nuisance  has 
been  created.  Decisions  enough  can  be  found 
to  justify  the  action  of  trespass  in  all  cases  of 
encroaching  signs,  buildings,  trees,  overhang- 
ing telegraph  and  telephone  wires;  but  in  all 
these  cases  the  defendant's  possession  and  the 
use  of  the  land  have  been  interfered  with.  It 
may  well  be  concluded  that  rights  in  the  air 
must  be  strictly  appurtenant  to  the  soil  beneath, 
and  that  unless  a  reasonable  use  of  the  land  is 
interfered  with,  no  action  for  trespass  will  lie. 
The  actual  interference  with  the  enjoyment 
of  the  land  as  the  sole  justification  for  legal 
action  is  fully  recognised  in  Europe.  Even  be- 
fore the  advent  of  the  flying-machine  and  the 
airship  the  code  of  the  Canton  of  Grisons  pro- 
vided that  "  property  in  land  extends  to  the  air 
space  (above)  and  the  earth  beneath,  so  far  as 
these  may  be  of  productive  value  to  the  owner." 
In  the  German  Civil  Code  the  rights  of  the  air- 
man are  recognised  in  a  clause  in  which  the 


25o    THE    NEW   ART    OF    FLYING 

property  holder  "  cannot  prohibit  such  interfer- 
ences undertaken  at  such  a  height  or  depth  that 
he  has  no  interest  in  the  prevention." 

It  is  probable  that  one  of  the  first  of  the  fu- 
ture laws  of  the  air  will  fix  the  height  at  which 
air-craft  must  travel.  In  all  likelihood  the  aero- 
naut will  be  compelled  to  sail  at  a  height  not 
less  than  fifteen  hundred  feet  over  inhabited 
districts  and  navigable  inland  waters,  leaving 
him  free  to  fly  at  any  height  he  pleases  over 
wildernesses  and  the  high  seas.  A  man  who 
sails  over  a  city  not  only  takes  his  own  life  into 
his  hands,  but  also  endangers  the  lives  of  others, 
because  he  cannot  readily  alight  should  his 
motor  fail  him.  The  French  advocate,  Fau- 
chille,  has  therefore  proposed  a  law  which  will 
forbid  flying  over  communities  without  the  per- 
mission of  the  authorities. 

That  an  action  can  be  brought  against  an 
aviator  who  alights  upon  a  piece  of  land  with- 
out the  owner's  permission,  even  though  he  be 
compelled  to  do  so  against  his  will,  is  even  now 
well  established.  In  a  New  York  case  (Guille 
v.  Swann,  19  Johns.  381 ;  10  Amer.  Dec.  234) 
decided  in  1822,  an  aeronaut  was  held  respon- 


THE    LAW   OF   THE   AIR       251 

sible  not  only  for  the  direct  damage  caused  by 
the  descent  of  his  balloon  into  a  garden,  but 
even  for  the  remote  damage  caused  by  the 
crowding  of  strangers  upon  the  property  to  sat- 
isfy their  curiosity.  Such  unpremeditated  de- 
scents will  be  frequent  in  coming  years.  The 
obvious  necessity  of  sometimes  alighting  against 
one's  will  demands  some  law  which  will  enable 
the  airman  to  land  without  necessarily  incurring 
a  suit  for  damages  or  imprisonment.  Judge 
Simeon  Baldwin  questions  whether  it  will  not 
be  advisable  to  prescribe  a  mode  of  indicating 
where  a  landing  is  prohibited  and  where  it  is 
permitted.  If,  for  instance,  a  red  flag  were 
made  the  sign  of  prohibition,  it  may  fairly  be 
provided,  in  his  opinion,  that  to  land  in  the  face 
of  such  a  warning  the  aviator  subjects  himself 
to  an  action  for  double  damages,  enforcible  by 
his  arrest.  The  Berlin  Conference  relating  to 
wireless  telegraphy  imposed  on  all  coast  and 
shipping  stations  the  duty  of  exchanging  wire- 
less messages,  regardless  of  the  system  em- 
ployed. A  similar  arrangement  would  probably 
apply  to  the  right  of  air-craft  to  use  local  areas 
set  apart  for  alighting,  mooring,  and  embarka- 


252    THE    NEW    ART    OF    FLYING 

tion.  It  would  seem  that  a  distinction  should 
be  made  between  an  accidental  landing,  which 
is  due  to  negligence  and  which  causes  damage, 
and  a  landing  which  is  made  with  all  due  care 
in  order  to  save  the  airman  from  death.  In 
the  one  case  a  penalty  of  some  kind  should  be 
imposed,  but  in  the  other  the  airman  should  be 
allowed  to  escape  by  simply  paying  the  amount 
of  the  actual  damage  which  he  has  inflicted. 
Judge  Baldwin  has  even  raised  the  question 
whether  the  law  of  self-preservation  cannot  be 
invoked  by  an  airman  who  is  compelled  to 
make  an  immediate  landing  to  save  his  own  life 
and  by  so  doing  accidentally  causes  the  death 
of  another. 

It  is  certain  that  in  order  to  reduce  the  possi- 
bility of  accidents  to  a  minimum  only  a  licensed 
pilot  will  be  permitted  to  navigate  the  air  in 
the  future.  Judge  Baldwin  advises  that  the 
government  issue  such  licenses  only  on  the 
filing  of  a  proper  indemnity  bond  for  the  bene- 
fit of  those  who  may  suffer  such  accidents. 
He  has  pointed  out  that  the  same  result  could 
be  obtained  by  compelling  the  owners  of  air- 
craft to  take  out  blanket  policies  of  accident 


THE    LAW   OF   THE   AIR       253 

insurance,  covering  all  injuries  occasioned  by 
the  use  of  the  ship  and  authorising  the  injured 
to  bring  suit  upon  it  in  the  name  of  the  insured, 
but  for  their  own  benefit. 

In  European  countries  a  tendency  is  shown 
to  subject  air  navigation  to  the  monopolistic 
control  of  the  state.  In  the  United  States  and 
in  England  private  enterprises  will  have  a  freer 
hand,  subject,  of  course,  to  strict  governmental 
supervision  by  registration,  license,  and  inspec- 
tion. But  shall  such  a  government  license 
issued  in  one  state  or  country  be  respected  in 
another?  There  seems  to  be  no  good  reason 
why  it  should  not.  Automobile  licenses  are  so 
respected  for  a  limited  number  of  hours. 
Treaties  and  agreements  will  undoubtedly  be 
drawn  which  will  secure  the  recognition  of  air 
licenses  by  foreign  governments.  But  to  har- 
monise the  aeronaut's  rights  with  those  of  other 
men  and  those  of  foreign  lands  over  which  he 
may  take  his  course,  demands  not  only  ade- 
quate local  legislation  but  adequate  interna- 
tional agreements.  Professor  Meli  of  Zurich, 
in  a  recent  address  before  the  International 
Vereinigung  fur  vergleichende  Rechtswissen- 


254    THE    NEW   ART    OF    FLYING 

schaft  of  Berlin,  strongly  advocated  the 
convening  of  an  international  conference  for 
this  purpose.  Such  a  conference  was  held  at 
Paris  in  1910,  but  accomplished  very  little  in 
the  way  of  practical  results.  The  British 
Government  demanded  more  time  for  con- 
sideration before  approving  the  measures  of 
the  Conference. 

Although  every  reasonable  concession  will 
be  made  to  the  man  who  builds  and  flies  air- 
craft, it  must  not  be  supposed  that  those  below 
are  altogether  at  the  mercy  of  the  man  in  the 
air.  Every  moment  of  an  atmospheric  voyage 
is  fraught  to  some  extent  with  danger  to  those 
below.  If  actual  physical  injury  is  sustained 
by  a  man  on  the  ground,  the  civil  or  criminal 
courts  may  be  appealed  to  for  justice.  The 
man  who  is  wounded  by  an  object  dropped 
from  an  air-craft  certainly  has  a  right  of  action 
for  damages,  whether  or  not  he  be  the  owner 
of  the  land  upon  which  he  happens  to  be  stand- 
ing at  the  time.  The  master  and  servant  rule 
would  apply  here  as  well  as  in  other  cases. 
An  action  for  damages  would  lie  against  the 
pilot  of  the  flying-machine,  whether  he  be  the 


THE    LAW   OF   THE   AIR       255 

owner  of  the  craft  or  not,  or  the  master  by 
whom  he  is  employed.  It  is  even  conceivable 
that  an  injunction  could  be  obtained  to  abate 
a  nuisance  caused  by  a  fleet  of  air-craft  travel- 
ling in  a  defined  roadway  day  after  day  and 
week  after  week,  so  as  to  annoy  a  tenant  or  a 
property  holder  by  their  noise,  odours,  exhaust, 
and  the  like. 

Besides  these  rights  of  the  man  below, 
whether  he  be  a  landowner  or  not,  there  are 
broader  national  questions  to  be  considered. 
In  a  sense  the  state  is  the  ultimate  owner  of 
the  soil,  and  as  such  it  has  the  right  to  regulate 
the  air  above  its  territory,  and  to  state  the  con- 
ditions under  which  it  will  permit  the  naviga- 
tion of  the  air.  That  air-craft  will  sooner  or 
later  become  the  subject  of  governmental  reg- 
ulation and  authorisation  seems  almost  self- 
evident  when  we  consider  the  history  of  the 
railroad,  the  telegraph,  the  telephone  and  wire- 
less telegraphy.  In  the  United  States  the  indi- 
vidual states  will  regulate  the  air-craft  that  ply 
the  air  wholly  within  the  state;  the  federal 
government  those  vessels  that  travel  from  state 
to  state. 


256    THE    NEW   ART    OF    FLYING 

The  international  aspects  of  the  question  are 
somewhat  more  difficult  to  dispose  of.  Before 
the  American  Political  Science  Association,  Mr. 
Arthur  K.  Kuhn  suggested  that  the  right  of 
the  craft  of  one  nation  freely  to  traverse  the 
air-space  of  another  might  be  compared  with 
that  of  the  vessel  of  one  state  freely  to  navi- 
gate the  river  of  a  coriparian  state,  especially 
when  the  river  becomes  navigable  within  its 
own  territory.  Dr.  Hazeltine,  reader  in  Eng- 
lish law  at  Cambridge,  believes,  however,  that 
the  analogies  of  the  high  seas  and  the  maritime 
belt  of  coastal  waters  as  applied  by  advocates 
of  limited  sovereignty  are  far  from  being  sound 
and  applicable.  Still  it  is  not  unlikely  that,  in 
settling  the  international  problems  that  must  in- 
evitably arise  in  the  future,  some  of  the  prin- 
ciples of  maritime  law  will  be  applied  to  the 
navigation  of  the  air.  Because  the  airship,  and 
to  a  lesser  degree  the  aeroplane,  may  be  an 
instrument  of  commerce  as  well  as  a  ship  sail- 
ing the  high  seas,  Judge  Baldwin  has  suggested 
that  provision  must  be  made  for  ship's  papers; 
that  the  number  of  passengers  to  be  carried  on 
an  air  vessel  must  be  fixed;  that  the  qualifica- 


THE    LAW   OF   THE   AIR       257 

tions  of  those  in  charge  must  be  determined; 
that  machinery  must  be  inspected;  and  that 
pilotage  must  be  provided  for. 

Freedom  of  the  seas  is  based  on  the  impos- 
sibility of  an  effective  control  by  any  one  state. 
It  has  been  urged  by  one  school  of  German 
advocates,  among  them  Meurer,  Holtzendorff, 
and  Griinwald,  that  the  air-space  over  a  state 
is  an  appurtenance  of  it,  and  as  such  the  right 
to  navigate  it  is  not  as  free  as  the  right  to  navi- 
gate the  high  seas.  By  another  school  the  rela- 
tion of  the  state  to  its  overlying  air-space  is 
compared  with  that  of  its  coastal  waters.  The 
abortive  Convention  drafted  by  the  International 
Conference  on  Aerial  Navigation  of  1910  was 
based  entirely  upon  the  provisions  of  inter- 
national maritime  law.  There  are  the  same  re- 
quirements as  to  registration  and  nationality  of 
air-vessels,  certificates  of  fitness  of  the  craft 
and  the  competence  of  its  navigators  and  navi- 
gation in  territorial  waters  —  using  the  mari- 
time phrase  for  the  sake  of  convenience  —  and 
the  same  regulations  applying  to  the  sojourn 
of  alien  craft  in  distress.  It  is  laid  down  that 
aerial  navigators  must  keep  a  very  detailed 


258    THE    NEW   ART    OF    FLYING 

log,  giving  the  names,  nationality  and  domicile 
of  all  persons  on  board,  and  embodying  a  record 
of  the  course,  altitude  and  all  the  events  of  the 
voyage.  This  log  must  be  preserved  for  at 
least  two  years  from  the  date  of  the  last  entry, 
and  must  be  produced  on  the  demand  of  the 
authorities.  Each  state  would  have  to  exercise 
the  right  of  police  and  customs  supervision  in 
the  atmosphere  over  its  territory.  It  would 
have  power  to  regulate  passenger  and  goods 
traffic  between  points  in  its  own  territories,  and 
it  could  prohibit  navigation  in  certain  zones  of 
reasonable  extent,  indicated  with  sufficient  pre- 
cision to  permit  of  their  being  shown  on  aero- 
nautical charts.  There  is  such  a  thing  as  a  three- 
mile  limit  in  maritime  law,  a  limit  originally  set 
by  the  range  of  a  cannon.  Why  then,  we  are 
asked,  should  there  not  be  sovereignty  within  a 
certain  zone,  the  height  of  which  is  determined 
by  gun  fire?  The  analogy  and  the  rule  re- 
sulting from  it  were  strongly  supported  by 
Westlake  before  the  Institute  of  International 
Law;  but  they  were  rejected  in  favour  of  a 
negative  sovereignty,  saving  the  right  of  self- 
protection.  The  range  of  Krupp  ordnance, 


THE   LAW   OF   THE   AIR       259 

which  has  been  especially  designed  for  airship 
repulsion,  would  no  doubt  aid  in  determining 
the  height  of  such  a  zone.  Holtzendorff,  Fau- 
chille,  and  Holland  would  restrict  absolute  sov- 
ereignty within  a  zone  of  isolation  varying  from 
three  hundred  and  thirty  metres  (the  altitude 
of  the  Eiffel  Tower  as  the  highest  artificial 
object)  to  fifteen  hundred  metres.  The  topog- 
raphy of  the  earth  is  in  itself  a  sufficient  objec- 
tion to  that  proposal.  Dr.  Hazeltine  has 
expressed  the  view  that  any  theory  of  sover- 
eignty limited  in  height  is  open  to  the  same 
objection  as  the  theory  of  a  zone  of  protection 
in  which  free  passage  is  allowed  to  non-military 
craft.  In  his  opinion  the  state  should  have  full, 
sovereign  dominion  in  the  entire  air  space 
above  its  territory.  Furthermore,  he  main- 
tains that  the  recognition  of  each  territorial 
state's  full  right  of  sovereignty  in  the  air  space 
above  it  would  constitute  a  basis  for  the  fu- 
ture development  of  national  and  international 
aerial  law,  leaving,  as  it  would,  to  aerial  navi- 
gators as  well  as  states  and  their  inhabitants 
the  full  legal  enjoyment  of  their  proper  interests. 
A  nation's  sovereignty  can  hardly  extend 


260    THE    NEW   ART    OF    FLYING 

to  a  domain  that  it  cannot  defend  from  invasion. 
When  Balboa  stood  upon  a  peak  in  the  Andes 
and,  surveying  the  Pacific,  claimed  in  the  name 
of  Spain  all  the  land  that  its  waters  might  wash, 
he  was  as  ridiculous  as  he  was  grandiloquent. 
Even  in  that  age  of  limited  geographical  knowl- 
edge he  must  have  felt  that  his  country  could 
never  uphold  the  claim  by  force  of  arms.  To  be 
sure,  it  would  be  easier  for  a  nation  to  defend  all 
the  air-space  above  its  territory  than  to  restrain 
encroachments  upon  land  washed  by  the  waters 
of  a  vast  ocean.  The  maximum  height  at  which 
air-craft  can  sail  may  be  placed  at  about  five 
miles,  with  the  probability  that  the  average 
height  will  be  about  one  mile.  It  would  not  be 
a  task  of  extraordinary  difficulty  for  any  nation 
equipped  with  a  formidable  aerial  navy  to  police 
its  air-space  more  or  less  effectively.  Whatever 
zone  is  adopted,  self-interest  alone  will  impel 
each  state  to  grant  access  to  and  passage 
through  its  air-space  in  time  of  peace,  subject 
only  to  such  rules  as  its  reasonable  interests  may 
require.  As  to  the  liberty  to  navigate  the  air, 
the  following  rule  was  accepted  at  the  Inter- 
national Conference  of  1910: 


THE   LAW   OF   THE   AIR      261 

"  Each  of  the  contracting  States  shall  permit 
the  navigation  of  the  airships  of  the  other  con- 
tracting States  within  and  above  its  territory, 
reserving  the  restrictions  necessary  to  guaran- 
tee its  own  safety  and  that  of  the  persons  and 
property  of  its  inhabitants." 

The  restrictions  referred  to  relate  chiefly  to 
the  question  of  certain  zones,  over  which,  if  they 
are  properly  indicated  in  advance,  no  airship 
may  fly  unless  compelled  to  by  necessity.  If 
an  aeroplane  is  carried  by  accident  or  by  adverse 
air  conditions  over  an  interdicted  zone,  it  must 
descend  at  once  and  indicate  its  disability.  It 
must  also  descend  if  signalled  to  from  the 
earth. 

The  matter  of  jurisdiction  over  crimes  com- 
mitted by  airmen  or  their  passengers  is  likewise 
a  matter  of  international  concern.  Fauchille  has 
proposed  that  crimes  committed  on  air-craft "  fall 
under  the  competence  of  the  tribunals  of  the 
nation  to  which  the  air-craft  belongs."  Ameri- 
can and  English  lawyers  will  object  to  any  such 
principle  because  Anglo-Saxon  law  has  always 
been  territorially  administered.  Probably  con- 
current jurisdiction  will  be  agreed  upon,  as  in 


262    THE    NEW   ART    OF    FLYING 

the  case  of  crimes  committed  on  foreign  vessels 
in  territorial  waters. 

Besides  crimes  committed  on  air-craft,  there 
are  also  crimes  committed  on  the  ground  which 
involve  the  rights  of  airmen.  Balloons  have 
been  shot  at  in  pure  wantonness.  Jurisdiction 
in  such  cases  obviously  belongs  to  the  country 
in  which  the  firearms  were  discharged.  If  a 
man  is  killed  in  a  flying-machine  in  the  United 
States  by  a  bullet  discharged  over  the  border- 
line in  Canada,  there  is  no  reason  why  murder 
has  not  been  done  in  the  United  States  and  why 
the  murderer  should  not  be  extradited  and  tried 
in  a  United  States  court. 

Lastly,  there  remains  to  be  considered  the 
legal  status  of  the  airship  and  the  aeroplane  in 
time  of  war.  Balloons  were  used  in  war  long 
before  the  dirigible  airship  or  the  aeroplane 
were  brought  to  a  state  of  practical  perfection, 
but  they  never  played  so  conspicuous  a  part  in 
military  operations  that  it  was  necessary  to  de- 
fine their  status  according  to  the  principles  of 
international  law.  It  is  true  that  Bismarck  said 
that  an  Englishman  who  manned  a  French 
balloon  would  be  subject  to  arrest  and  trial 


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THE   LAW   OF   THE   AIR       263 

"  because  he  had  spied  out  and  crossed  our  out- 
posts in  a  manner  which  was  beyond  the* con- 
trol of  the  outposts,  possibly  with  a  view  to 
making  use  of  the  information  thus  gained  to 
our  prejudice."  That  dictum  of  blood  and  iron 
seems  much  too  drastic  even  to  German  com- 
mentators. A  spy  is  supposed  to  act  clandes- 
tinely. An  air-craft  is  so  conspicuous  an  object 
that  even  though  bent  on  ascertaining  the 
enemy's  strength  and  the  disposition  of  its 
forces,  its  errand  can  hardly  be  secret.  On  the 
other  hand,  Mr.  Kuhn  has  pointed  out  that  the 
impossibility  of  flying  secretly  by  day,  at  least, 
is  in  itself  no  reason  why  the  use  of  the  air- 
craft may  not  be  clandestine.  The  Hague 
Peace  Conference  in  1907  left  the  matter  in  a 
very  unsatisfactory  condition.  It  provided  that 
aeronauts  were  not  to  be  regarded  as  spies  if 
they  carried  despatches  or  maintained  commu- 
nication between  different  parts  of  an  army  or 
territory,  but  it  failed  to  fix  the  status  of  the 
reconnoitring  airman.  In  the  war  of  the  future 
the  aeroplane  and  the  airship  will  perform 
much  the  same  function  as  a  cavalry  reconnais- 
sance in  force;  yet  even  Bismarck  would  not 


264    THE    NEW   ART   OF    FLYING 

have  shot  as  a  spy  a  trooper  captured  on  a 
scouting  raid.  The  international  complica- 
tions which  may  arise  even  at  the  present  time 
will  undoubtedly  be  considered  when  the  next 
Hague  International  Conference  takes  place. 
The  possibility  that  an  alert  military  spy,  float- 
ing serenely  over  a  fortress  which  has  cost  a 
nation  millions,  may  photograph  or  sketch 
every  battery,  manifestly  necessitates  the  adop- 
tion of  some  restrictive  measures.  So  jealously 
are  many  of  the  fortifications  of  Europe 
guarded  from  the  watchful  eyes  of  spies,  that 
entry  within  their  portals  is  granted  only  on 
certain  conditions.  No  cameras  may  be  taken 
within  the  lines;  nor  is  admission  granted  with- 
out credentials.  What  a  spy  on  land  might  be 
unable  to  discover  in  months  by  cunning,  cajol- 
ery, and  bribery,  will  be  exposed  to  an  aeronaut 
in  half  an  hour.  Some  check  must  therefore  be 
placed  upon  the  scout  in  the  air.  At  the  Inter- 
national Conference  on  Aerial  Navigation  of 
1910  it  was  proposed  that  a  state  should  have 
the  privilege  of  developing  photographic  nega- 
tives found  on  board  an  airship  coming  to  earth 
in  its  territory,  and  if  necessary  to  seize  them 


THE   LAW   OF   THE   AIR      265 

and  the  photographic  apparatus.  Wireless  tele- 
graphic instruments,  too,  could  not  be  used, 
according  to  another  provision,  without  special 
permission,  for  any  other  purpose  than  to  secure 
the  vessel's  safety.  Perhaps,  although  no  Inter- 
national Conference  has  thus  far  suggested  it, 
the  pilots  of  the  future  will  be  constrained 
to  avoid  fortifications  entirely,  or  run  the  risk 
of  arrest  by  air  sentry,  —  military  lookouts 
gliding  along  in  aeroplanes  ready  to  act  if  a 
too  closely  approaching  atmospheric  tourist  ap- 
pears. Arrests  will  undoubtedly  be  made  by 
these  sentinels  in  the  air;  the  captured  aeronaut 
will  be  asked  for  his  credentials  and  will  be 
searched  for  sketches  that  may  implicate  him. 
If  he  is  caught  red-handed,  he  will  be  punished 

—  how,  must  be  determined  by  international 
agreement. 

The  war  of  the  future  will  be  a  conflict  of  air- 
craft as  well  as  of  infantry  and  artillery.  How 
shall  the  aeroplane  of  any  warring  country  be 
distinguished  from  those  of  any  other?  Every 
ship  on  the  high  seas,  whether  it  be  merchant- 
man or  battleship,  flies  the  flag  of  its  country, 

—  a  challenge  to  its  foes  in  time  of  war,  a 


266    THE    NEW    ART    OF    FLYING 

badge  of  peace  to  its  friends.  The  question 
of  nationality  brought  up  some  interesting  points 
during  the  International  Conference  of  1910. 
It  was  decided  that  it  should  be  determined  by 
the  nationality  of  the  owner  or  by  his  domicile. 
It  was  also  voted  that: 

"  A  State  may  require  its  subject  to  be  at  the 
same  time  domiciled  on  its  territory,  or  it  may 
admit  domiciled  foreigners  as  well  as  its  sub- 
jects. Airships  belonging  to  companies  must 
take  the  nationality  of  the  State  in  which  their 
head  office  is  situated.  In  the  case  of  an  airship 
belonging  to  several  owners,  at  least  two-thirds 
must  be  owned  by  subjects  of,  or  foreigners 
domiciled  in,  the  State  conferring  nationality." 

The  Swiss  delegates  protested  that  this  article 
would  permit  the  establishment  of  many  foreign 
airships  in  one  nation  without  the  supervision  of 
their  own,  and  then  drew  attention  to  a  sugges- 
tion already  made  by  them  that  no  nationality 
be  attributed  to  airships,  but  that  each  airship 
be  compelled  to  acknowledge  a  "  certain  port 
of  register  or  domicile."  This  system,  the  Swiss 
believe,  "  offers,  from  the  point  of  view  of  the 
safety  of  States,  guarantees  very  superior  to 


THE    LAW   OF   THE   AIR       267 

those  secured  by  the  system  of  owner's  na- 
tionality." But  the  Swiss  proposal  was  rejected. 

Fully  as  important  as  these  considerations 
are  the  rights  of  neutral  air-craft  in  time  of 
war.  If  France  and  Russia  are  at  war,  has 
Germany  the  right  to  prevent  the  v  vessels  of 
either  nation  from  crossing  her  boundaries  be- 
cause her  neutrality  is  violated?  The  right  of 
exclusion  is  absolute,  if  no  neutral  zone  be 
agreed  upon  internationally.  But  if  a  free 
zone  be  agreed  upon,  the  aerial  equivalent  of 
the  maritime  three-mile  limit,  have  belligerents 
the  right  to  engage  in  battle  over  neutral  ter- 
ritory with  a  possibility  of  injuring  those  below? 
There  is  such  a  force  as  gravitation  and 
with  that  force  airships  and  aeroplanes  must 
constantly  reckon. 

Will  the  air-craft  that  seeks  refuge  on  neutral 
ground  or  in  neutral  air  be  compelled  to  leave 
within  a  stipulated  time,  as  in  the  case  of  a 
warship  that  seeks  refuge  in  a  neutral  harbor? 
Will  an  air-craft  so  badly  injured  that  it  cannot 
leave,  even  when  ordered  to  do  so,  be  disarmed? 

The  military  reports  of  the  question  were 
discussed  at  the  International  Conference  of 


268     THE    NEW    ART    OF    FLYING 

1910,  but  more  with  regard  to  the  status  of 
air-craft  in  time  of  peace  than  in  time  of  war. 
The  departing  or  landing  of  military  airships 
of  one  state  in  the  territory  of  another  was 
prohibited,  unless  with  the  authorization  of 
the  state  whose  territory  is  involved;  -while 
each  contracting  state  was  at  liberty  to  pro- 
hibit or  regulate  in  accordance  with  its  interests 
the  passage  over  its  territories  of  military  air- 
ships belonging  to  other  contracting  states.  A 
clause  in  the  Convention  relating  to  the  extra- 
territoriality of  military  airships  and  their  crews 
while  within  the  limits  of  jurisdiction  of  a  for- 
eign state,  appears  not  to  have  met  with  the  full 
approval  of  the  delegates  of  several  Powers, 
Great  Britain  and  Austria  being  among  those 
who  reserved  their  adhesion.  The  Convention 
stipulated  that  nothing  it  contained  should  in- 
terfere with  the  liberty  of  action  of  belligerents 
or  with  the  rights  and  duties  of  neutrals.  As 
bearing  on  this  point,  it  is  of  interest  that  all 
the  participating  nations  agreed  that  the  aerial 
transport  of  explosives,  firearms,  ammunitiqn, 
and  carrier-birds  must  be  forbidden. 


GLOSSARY 

Adjusting  Plane  or  Adjusting  Surface:  A  surface 
of  small  area  for  regulating  lateral  stability;  usually 
located  at  the  side  edge  or  rear  edge  of  a  supporting 
plane.  It  is  to  be  distinguished  from  an  aileron  (q.  v.) 
in  that  it  is  capable  of  adjustment  but  not  of  inde- 
pendent movement  by  special  operating  devices. 

Advancing  Edge:     See  Entering  Edge. 

Advancing  Surface:  The  forward  supporting  sur- 
face of  a  machine  provided  with  supporting  planes  in 
tandem,  as  in  the  Langley  aerodrome,  or  with  super- 
posed surfaces  arranged  in  step  formation. 

Aerocurve:  Any  arched  supporting  surface.  The 
term  has  been  proposed  because  few  supporting  sur- 
faces are  true  aeroplanes.  See  also  Aerofoil. 

Aerodrome:  A  term  invented  by  the  late  Prof. 
Samuel  P.  Langley  and  used  by  him  to  designate 
an  aeroplane  flying-machine.  Etymologically  the  term 
signifies  "  air-runner."  It  is  more  commonly  used  to 
designate  a  flying-course  by  analogy  with  "  hippo- 
drome." Mr.  F.  W.  Lanchester  and  Dr.  Alexander 
Graham  Bell  have  sought  to  restrict  the  term  to  th& 
use  which  Langley  intended. 

Aerodromics:  Langley 's  term  for  the  science  and  art 
of  flying  with  an  aeroplane  flying-machine. 

Aerofoil:  The  supporting  surface  of  a  flying- 
machine,  coined,  like  Aerocurve,  because  the  sup- 
porting surfaces  of  a  flying-machine  are  not,  strictly 
speaking,  flat  planes. 


270  GLOSSARY 

Aeronaut:  One  who  navigates  the  air. 

Aeronautics:  The  science  of  aerial  navigation. 

Aeronef:  A  term  invented  in  France  and  intro- 
duced into  English-speaking  countries  to  designate  any 
heavier-than-air  flying-machine.  The  term  is  not  much 
employed  either  in  French  or  in  English. 

Aeroplane:  Any  plane  surface  propelled  through  the 
air.  The  term  was  invented  before  it  was  discovered 
that  curved  surfaces  are  better  than  flat  surfaces. 
Hence  it  is  not  strictly  applicable  to  modern  support- 
ing surfaces. 

Aileron:  A  French  word  meaning  "  winglet,"  in- 
troduced into  English  to  designate  any  freely  swinging 
surface  controlled  by  the  aviator  and  designed  to  main- 
tain lateral  stability.  Ailerons  may  be  either  tips 
hinged  to  the  side  edges  or  rear  edges  of  the  main 
supporting  surface,  or  they  may  be  small  independent 
planes.  See  also  Adjusting  Surface,  Balancing  Plane 
or  Surface,  Stabiliser,  and  Wing-Tip. 

Airship:  A  term  originally  employed  to  designate 
any  aerial  craft,  whether  heavier  or  lighter  than  air, 
but  now  restricted  by  the  best  writers  to  dirigible 
balloons. 

Air  Speed:  The  velocity  of  a  machine  in  the  air  as 
distinguished  from  its  velocity  on  the  ground. 

Airman:  An  aeronaut;   one  who  navigates  the  air. 

Alighting  Gear:  The  wheels  or  skids  or  combina- 
tions of  both  on  which  a  machine  alights.  See 
Skids. 

Angle  of  Attitude:   See  Angle  of  Incidence. 

Angle  of  Entry:  The  angle  formed  by  a  tangent  to 
the  entering  edge  with  the  line  x>f  motion. 

Angle  of  Incidence:   The  angle  made  by  the  main 


GLOSSARY  271 

planes  with  the  line  of  travel.  Sometimes  called 
"  angle  of  attitude  "  and  "  angle  of  attack."  The  angle 
may  be  positive  or  negative,  depending  on  the  direction 
in  which  the  plane  is  turned  to  the  line  of  flight. 

Angle  of  Trail:  The  angle  formed  by  a  tangent  to 
the  rear  edge  with  the  line  of  travel  in  curved  sup- 
porting surfaces. 

Apteroid:  Lanchester's  term  for  a  short,  broad  form 
of  wing. 

Arch:  The  downward  curve  or  droop  to  the  ends 
of  supporting  surfaces. 

Aspect:  The  top  plan  view  of  an  aeroplane  flying- 
machine. 

Aspect  Ratio:  The  ratio  of  the  length  to  the  width 
of  a  plane  or  curved  supporting  surface. 

Aspiration:  The  suction  produced  by  a  current  of 
air  which  strikes  a  curved  supporting  surface. 

Attitude:    See  Angle  of  Incidence. 

Automatic  Stability:    See  Stability. 

Auxiliary  Surface:     See  Supplementary  Surface. 

Aviation:  Flight  with  heavier-than-air  machines  as 
distinguished  from  ballooning. 

Aviator:  The  pilot  of  a  heavier-than-air  machine. 

Balance:  The  maintenance  of  equilibrium  by  means 
of  balancing  surfaces.  A  distinction  is  sometimes  made 
between  Balancing  and  Stabilising  (q.  v.). 

Balancing  Plane  or  Balancing  Surface:  A  surface  for 
establishing  and  maintaining  equilibrium  as  well  as  to 
assist  in  turning.  Such  surfaces  may  be  operated  either 
automatically  or  by  hand;  they  maintain  both  longi- 
tudinal and  lateral  balance. 

Beat:  A  periodically  recurring  movement  in  a  pro- 
peller blade  or  in  a  wing  of  a  flapping-wing  machine. 


272  GLOSSARY 

Biplane:  A  flying-machine  with  two  superposed  sup- 
porting surfaces. 

Body:   See  Fuselage. 

Box-Kite:  A  kite  invented  by  Hargrave  and  pro- 
vided with  two  parallel  vertical  and  two  parallel  hori- 
zontal surfaces  in  the  form  of  an  open  box. 

Brace:  A  compression  member. 

Camber:  The  curve  of  a  supporting  surface  meas- 
ured from  port  to  starboard. 

Caster-Wheel:  A  small  wheel  of  the  alighting  gear, 
so  pivoted  that,  like  the  caster  of  a  chair,  it  automati- 
cally suits  itself  to  the  direction  of  the  flying-machine's 
motion  on  the  ground. 

Carburetter:  An  apparatus  by  which  air  is  charged 
with  a  hydrocarbon  so  that  it  will  either  burn  or  ex- 
plode. In  the  gasoline  flying-machine  motor  it  serves 
the  purpose  of  mixing  the  gasoline  vapor  with  air 
in  the  right  proportion  to  form  an  explosive  when 
ignited. 

Chassis:  The  under  framework  of  a  flying-machine. 

Cell:  An  open  box-like  unit.  Its  parallel  vertical 
and  parallel  horizontal  surfaces  serve  to  maintain 
stability. 

Centre  of  Effort:  The  point  in  which  the  effect  of 
an  axially  exerted  force  is  theoretically  concentrated, 
as,  for  example,  the  thrust  of  a  propeller. 

Centre  of  Gravity:  A  point  in  which  the  weight  of 
a  flying-machine  is  theoretically  concentrated. 

Centre  of  Lift:   See  Centre  of  Pressure. 

Centre  of  Pressure:  An  imaginary  centre  in  which 
the  air  pressure  on  a  supporting  surface  is  theoretically 
concentrated. 

Centre  of  Thrust:  See  Centre  of  Effort. 


GLOSSARY  273 

Chord:  The  line  connecting  the  ends  of  the  segment 
of  a  circle. 

Compound  Control:  A  system  of  hand-levers  and 
ropes  or  hand-wheels  and  ropes  by  which  two  con- 
trolling operations  are  simultaneously  carried  out  with 
but  a  single  operating  device,  as,  for  example,  the 
single  lever  in  a  Wright  machine,  which  serves  not 
only  to  warp  the  main  planes,  but  also  to  swing  the 
vertical  rudder  at  the  same  time. 

Compression  Side:  The  side  of  a  surface,  such  as  an 
aeroplane  or  air-propeller,  which  faces  the  flow  of  air 
current. 

Curtain:  A  vertical  plane,  as  in  the  Voisin  cellular 
biplane,  between  the  main  planes,  serving  to  insure  a 
certain  amount  of  lateral  stability. 

Diagonal:   A  diagonal  brace  in  a  framework. 

Derrick:  A  pyramidal  structure  from  the  top  of 
which  a  weight  can  be  mechanically  dropped  in  order 
to  start  a  flying-machine  in  motion  on  a  rail.  Some- 
times called  a  "  pylon." 

Dihedral  Angle:  The  angle  formed  by  two  planes 
placed  at  opposite  sides  of  a  median  line,  so  as  to  form 
a  very  wide  "  V." 

Double-Decker:   A  synonym  of  biplane  (q.  v.). 

Double  Monoplane:  A  machine  having  two  sets  of 
supporting  surfaces  arranged  in  a  single  tier.  Such 
a  machine  is  also  called  a  "  following-surface " 
machine. 

Double  Rudder:  A  rudder  having  two  surfaces  of 
more  or  less  similar  surface  and  outline,  which  sur- 
faces may  or  may  not  act  simultaneously. 

Doubled-Surfaced:  Covering  both  sides  of  the 
framework  of  a  supporting  surface. 


274  GLOSSARY 

Drift:  The  resistance  offered  to  forward  motion  of 
a  plane  or  curved  surface  in  the  air  by  the  horizontal 
component  of  the  air  pressure  against  the  plane.  It  is 
to  be  carefully  distinguished  from  mere  head  resist- 
ance (q.  v.). 

Elevator:  The  horizontal  rudder  of  a  flying-machine, 
used  for  steering  in  a  vertical  plane. 

Entering  Edge:  The  front  or  leading  edge  of  an 
aeroplane. 

Equilibrator:   The  tail  of  a  flying-machine. 

Equilibrium:  In  flying-machine  parlance  the  term 
is  used  in  the  same  sense  as  "  stability."  Properly 
speaking,  an  aeroplane  is  in  equilibrium  when  travelling 
at  a  uniform  rate  in  a  straight  line,  or,  again,  when  it 
is  steered  around  a  horizontal  arc  or  circle.  It  is 
necessary  for  stability  that  if  the  aeroplane  be  not  in 
equilibrium  and  moving  uniformly  it  shall  tend  toward 
a  condition  of  equilibrium. 

Equivalent  Head  Area:  The  area  which  would  offer 
head  resistance  equal  to  that  of  the  supporting  sur- 
faces of  a  flying-machine  plus  the  struts,  stays,  wires, 
chassis,  etc. 

Feathering:  Said  of  surfaces  which  are  manoeuvred 
in  a  manner  to  pass  edgewise  and  flatwise  in  alternate 
directions  while  in  motion. 

Fin:  A  rigid  vertical  surface  which  acts  somewhat 
like  the  keel  of  a  sailing  yacht. 

Fish  Section:  A  section  resembling  in  shape  the  body 
of  a  fish.  Such  sections  are  commonly  found  in  flying- 
machine  struts. 

Fixed  Wheel:  In  contradistinction  to  a  caster-wheel 
(q.  v.),  a  wheel  that  always  preserves  its  relative  posi- 
tion in  the  alighting-gear. 


GLOSSARY  275 

Flapping-Wing  Flight:  Flight  by  means  of  beating 
wings  as  distinguished  from  flight  obtained  by  means 
of  rigid  aeroplanes.  See  Ornithopter. 

Flexible  Propeller:  A  fabric  propeller,  capable  of 
adjusting  itself  in  flight. 

Flying  Angle:  Flying  attitude.  See  Angle  of 
Incidence. 

Following  Edge:  The  rear  edge  of  an  aeroplane 
surface. 

Following  Surface:  The  rear  surfaces  of  two  similar 
surfaces  arranged  in  tandem. 

Fore-and-Aft:   Longitudinally. 

Front  Control:  Front  Rudder:  The  framework  and 
planes  situated  at  the  extreme  front  of  the  aeroplane, 
in  advance  of  the  operator. 

Fusiform :   Spindle-shaped. 

Fuselage:  The  framework  or  body  of  an  aeroplane. 

Gap:  The  distance  between  two  planes  in  a  multi- 
plane machine. 

Glide:   To  travel  without  power. 

Glider:  An  aeroplane  without  a  motor. 

Gliding  Angle:  The  angle  at  which  a  machine  glides 
down  without  power. 

Ground  Attitude  or  Incidence:  The  difference  in  the 
angle  formed  by  the  aeroplane  surface  when  on  the 
ground  and  when  in  flight. 

Guy-Wire:  A  wire  connecting  two  members  of  an 
aeroplane,  usually  parts  of  the  controlling  system. 

Gyroplane:  A  flying-machine  with  rotating  planes. 
See  Heliocopter. 

Gyroscope:  A  freely-hung,  rapidly-rotating  fly-wheel, 
which  resists  forces  that  tend  to  throw  it  from  its  plane 
of  rotation. 


276  GLOSSARY 

Hangar:  A  term  said  to  be  of  Hungarian  origin, 
now  also  used  in  English,  to  designate  a  shed  for  hous- 
ing aeroplanes  or  airships. 

Head  Area:  The  total  head  resistance  offered  by  the 
entire  framework  of  an  aeroplane. 

Head  Resistance:  The  resistance  a  surface  offers  to 
movement  through  the  air. 

Heavier-than-Air:  A  term  applied  to  all  air-craft 
not  sustained  by  a  buoyant  gas. 

Helicopter  or  Helicopter e:  A  heavier-than-air  ma- 
chine in  which  flight  is  secured  by  lifting  screw  pro- 
pellers revolving  in  more  or  less  horizontal  planes. 

Helix:  The  path  of  a  point  moving  uniformly 
around  a  cylinder  and  uniformly  along  the  cylinder. 

Horizontal  Rudder:   See  Elevator. 

Keel:  The  under  framing  of  an  aeroplane  to  stiffen 
it  both  laterally  and  vertically.  Sometimes  used  as  a 
synonym  of  fin  ( q.  v. ) . 

Land  Speed:  The  rate  of  travel  of  an  aeroplane  on 
the  ground  before  ascension. 

Landing  Area:  A  special  allotment  of  ground  on 
which  a  machine  can  land  safely. 

Landing  Skid:   See  Skid. 

Lateral:  A  strut  for  side  wise  bracing  in  the  frame- 
work of  an  aeroplane. 

Lateral  Stability:  Lateral  equilibrium  in  the  side-to- 
side  direction. 

Lattice  Girder:  A  girder  with  many  crossed  mem- 
bers, resembling  in  appearance  a  lattice  window. 

Leeway:  Lateral  drift  in  the  direction  in  which  the 
air  current  is  flowing  due  to  the  air  current. 

Lift:  The  ascensional  force  of  an  aeroplane  surface. 

Longitudinal  Stability:    Lengthwise  stability. 


GLOSSARY  277 

'Magneto:  An  apparatus  for  generating  electric  cur- 
rent to  produce  a  spark  wherewith  to  ignite  the  explo- 
sive mixture  in  the  cylinder  of  an  internal-combustion 
motor. 

Main  Plane:  The  largest  supporting  wing  in  a 
multiplane. 

Mast:  A  spar  or  strut  for  fastening  trussing  wires 
or  stays  to  stiffen  the  planes. 

Monoplane:  An  aeroplane  with  one  or  more  sup- 
porting surfaces,  all  in  the  same  plane. 

Monorail:  A  rail  used  as  a  track  in  starting  some 
machines. 

Multiplane:  An  aeroplane  with  more  than  one  main 
supporting  surface. 

Nacelle:  See  Fuselage.  In  some  monoplanes  the  en- 
closed, boat-like  part  of  the  body,  containing  the  seat 
for  the  pilot  and  his  passenger. 

Negative  Angle  of  Incidence:  The  angle  formed  by 
a  plane  inclined  downwardly  to  the  direction  of  travel. 

Ornithopter,  Ornithoptere,  Orthopter,  or  Orthop- 
tere:  A  machine  which  attains  flight  by  bird-like  flap- 
ping of  wings. 

Orthogonal  Action:  The  vertical  reaction  of  the  air 
in  affording  equilibrium  by  means  of  wing  motion. 

Panel:  The  vertical  planes  in  a  box-like  or  cellular 
structure. 

Pendular  Movement:  To-and-fro  movement  like 
that  of  a  pendulum. 

P  hug  old:  Lanchester's  designation  for  the  undulat- 
ing course  naturally  adopted  by  plane  surfaces  when 
moving  in  the  air. 

Pitch:  The  forward  movement  that  would  be  pro- 
duced by  one  turn  of  a  propeller  in  a  solid. 


278  GLOSSARY 

Plane:  Literally  a  flat  surface;  in  aeroplanes  a  flat 
or  curved  surface. 

Poly  plane:   See  Multiplane. 

Pylon:  The  tower  required  by  some  types  of  aero- 
planes to  start.  Also,  the  pillars  that  mark  a  definite 
course  to  be  taken  by  a  flying-machine  at  a  flying- 
machine  meeting. 

Radiator:  A  coil  of  piping  or  any  circuitous  conduit 
in  which  water  is  cooled  by  radiation  after  having  cir- 
culated around  the  hot  cylinder  of  an  internal  com- 
bustion engine. 

Rarefaction  Side:  The  side  opposite  the  compression 
side,  as,  for  example,  the  top  of  an  aeroplane  in  motion. 

Reactive  Stratum:  The  compressed  or  rarefied  layer 
of  free  air  flowing  along  an  aeroplane  surface. 

Rear  Control:  A  stabilising  tail  surface  which  may 
also  be  a  rear  horizontal  rudder. 

Rising  Angle:  The  maximum  angle  of  ascension.- 

Rudder:  A  horizontal  or  vertical  plane  used  for 
steering. 

Runner:  See  Skids. 

Screw:  A  propeller. 

Single-Decker:  A  monoplane. 

Single-Surfaced:  Aeroplane  surfaces  covered  only  on 
one  side.  Compare  with  Double-Surfaced. 

Skids:  Runners  underneath  some  types  of  machines, 
used  for  landing. 

Skin  Friction:  The  friction  of  the  air  against  sur- 
faces. 

Slip :  The  difference  between  the  pitch  of  a  propeller 
and  its  actual  forward  travel. 

Soaring  Flight:   Flight  with  rigid  wings. 

Spar:  A  strut,  a  brace,  etc. 


GLOSSARY  279 

Stability:  Maintenance  of  balance  in  flight  by  auto- 
matic devices  such  as  a  shifting  weight  or  a  gyroscope 
(q.  v.)  ;  or  hand-operated  devices  such  as  ailerons,  wing- 
tips,  and  plane-warping  devices. 

Stabilise:  To  maintain  equilibrium  by  means  of 
surfaces  and  not  by  mechanism. 

Stabiliser:  The  tail  of  a  flying-machine. 

Stabilising  Plane:  A  surface  for  the  maintenance  of 
equilibrium ;  small  horizontal  planes  hinged  to  the  main 
planes,  and  suiting  the  angle  of  the  wind. 

Starting  Frame:   See  Chassis. 

Starting  Rail:   See  Monorail. 

Stay:  A  brace  or  wire  in  an  aeroplane  framework. 

Steadying  Vane:  Small  vertical  planes,  usually  placed 
in  the  front  control  of  the  old  Wright  machine. 

Straight  Pitch:  In  propellers,  a  flat  instead  of  a 
helical  blade  surface. 

Strainer:   A  turnbuckle. 

Strut:  A  compression  member  in  a  structure.  In 
biplanes  the  posts  separating  the  main  planes. 

Supplementary  Surface  or  Auxiliary  Surface:  A 
small  surface  such  as  an  aileron  or  wing-tip,  which 
acts  in  unison  with  a  larger  one  for  a  specific  purpose. 

Supporting  Surfaces:   The  main  planes. 

Tail:  A  collective  term  for  the  framework  and 
planes  in  the  rear  of  the  main  plane. 

Tail  Planes:  The  rear  planes  supported  by  the  tail 
framework. 

Tail  Wheel:  A  small  wheel  under  the  tail  of  some 
machines  to  support  the  tail  on  the  ground. 

Tie:  A  tension  member  in  a  framework;  used  also 
for  wire  stays. 

Tractor  Screw:   A  propeller  set  in  front  of  the  sup- 


280  GLOSSARY 

porting  surface  instead  of  in  the  rear,  so  that  the  ma- 
chine is  drawn  through  the  air  and  not  pushed. 

Triplane:   An  aeroplane  with  three  superposed  sup- 
porting surfaces. 

Turnbuckle:  A  combined  right  and  left-hand  screw 
for  taking  up  the  slack  in  a  loose  wire  stay. 

Up-Wind:    Moving  against  the  wind. 

Variable  Pitch:    In  propellers,  a  varying  angle  of 
blade  width  in  contradistinction  to  uniform  pitch. 

Vol-Plane:   See  Glide. 

Wake:  The  wash  of  an  aeroplane  in  flight. 

Warping:  The  act  of  twisting  a  plane  for  the  main- 
tenance of  equilibrium. 

Wash:   See  Wake. 

Wing  Arc:  The  arc  described  by  a  moving  wing. 

Wing-Bar:   A    longitudinal    strip    so    placed    as   to 
strengthen  an  aeroplane  surface. 

Wing  Section:  The  longitudinal  curvature  with  re- 
lation to  the  arc  of  travel. 

Wing-Skid:  A  runner  under  a  wing-tip. 

Wing-Tip:   The  hinged  outer  side  of  a  plane. 

Wing-Wheel:  A  wheel  under  a  wing-tip  to  support 
the  wing  when  the  machine  strikes  on  the  ground. 


INDEX 


ACCIDENTS 

perils  of  flight,  161 

AEROCURVES  (See  Aeroplanes, 
Entering  Edge,  Lift,  and 
Planes) 

AERODYNAMICS 

empirical  formulae,  27; 
laboratories  and  their  work, 
38;  towing  carriage,  39; 
Eiffel's  experiments,  39;  whirl- 
ing tables,  40;  relative  ad- 
vantages of  fixed  and  moving 
models,  40;  Gottingen  studies, 
41;  propeller-thrust  tests,  106 

AEROLOGY  (See  Meteorology) 

AEROPLANE  (See  also  Entering 
Edge,  Planes,  Lift,  Drift) 

definition,  i;  compared 
with  kite,  2;  with  screw- 
propeller,  96;  military  uses, 
185;  dirigible  airships  vs. 
aeroplanes  in  war,  202;  aero- 
plane of  the  future,  236,  240 

AILERONS  (See  also  Stability) 

use  in  maintaining  stabil- 
ity, 61,  75;  Farman  system, 
69;  early  Antoinette  system, 
73;  use  in  turning,  88 

AIR 

relation  of  scientific  study 
of  air  to  flight,  133  et  seq.; 
study  by  de  Bort  at  great 
heights,  140;  charting  ocean 
of  air,  153  et  seq.,  241;  dangers 
of  unsteady  air,  163  et  seq.; 
air  resistance  and  effect  on 
structure  of  machines,  177, 
1 80;  military  command  of 
the  air,  186,  206;  effect  of 
rarefied  air  on  engines,  205 

AIRSHIPS  IN  WAR  (See  Explo- 


sives, Hague  Peace  Conference, 
and  War) 

ALBATROSS 

aspect  ratio,  16 

ALIGHTING 

birds  and  machines  com- 
pared, 13;  alighting  at  high 
speed,  36;  use  of  wheels  and 
shock  absorbers,  55,  167; 
skids,  55;  brakes,  57;  dangers, 
167,  179;  alighting  gear  of 
Farman,  56,  219;  of  Sommer, 
56;  of  Santos-Dumont,  56, 
229;  of  Antoinette  mono- 
plane, 56,  223;  Wright 
alighting  gear,  213;  Curtiss' 
alighting  gear,  216;  Bleriot 
XI  alighting  gear,  227;  alight- 
ing grounds  of  the  future, 
237;  landing  on  warships, 
238;  legal  aspects  of  com- 
pulsory landing,  251 

ALLARD 

ornithopter  experiments,  24 

ANEMOMETER 

use    in    meteorology,    134, 

139 

ANTOINETTE    (See  Monoplanes, 

Motors,  Stability) 
ANZANI  MOTOR  (See  Motors) 
ARCHITECTURE 

effect  of  flying  on  building 
design,  237 
ARMENGAUD  PRIZE 

won  by  Farman,  89 
ARTILLERY,   AERIAL   (See  Ord- 
nance) 
ASSMANN,  RICHARD 

meteorological  studies,  137, 
143,  144,  149,  154,  156,  158, 
159 


282 


INDEX 


ASPECT  RATIO 

in   birds,    16;     in   biplanes 
and  monoplanes,  16;   relation 
to  entering  edge  and  lift,  27 
ATMOSPHERE 

its    purpose,     133;    results 
of    study,     146;      isothermal 
stratum,     151;      permanent- 
inversion  layer,   151 
AUBRUN 

in  Circuit  de  I'Est,  131 
AUTOMOBILE      MOTORS       (See 

Motors) 
AUTOMOBILES 

motor-car  guns,  198;  Ehr- 
hardt  car,  200 


BALANCING  (See  Stability) 

BALANCING-PLANES  (See  Sta- 
bility) 

BALDWIN,  SIMEON 

on  law  of  the  air,  251,  252, 
256 

BALLOONS  IN  WAR  (See  Explo- 
sives, Hague  Peace  Conference, 
and  War) 

BALLOONS,  SOUNDING 

use  in  meteorology,  136, 
139,  143  et  seq. 

BANKING  (See  Steering  and 
Gravitation) 

BAROMETER 

its  use  in  flying,  134 

BAROTHERMOGRAPH 

meteorological  use,  140 

BELLENGER,  CAPTAIN 

performances  as  an  air- 
scout,  192,  194 

BIPLANE 

distinguished  from  mono- 
plane, 15,  16,  208;  structural 
advantages,  17;  defects  of  its 
double  surface,  18;  relative 
perfection  of  monoplane  and 
biplane,  18;  compared  with 
skate,  I;  control  of  center 
of  air-pressure  on  Wright 
machine,  8,  210;  tailed  and 
tailless  Wright  biplanes,  9,  17, 


95,  98,  103,  105,  209;  small 
wings  of  Wright  racers,  36, 
209,  213;  alighting  gear  of 
Wright  machine,  55,  213;  of 
Farman,  56,  219;  of  Sommer, 
56;  _of  Curtiss,  57;  of  old 
Voisin,  57;  structure  of 
Wright  machine,  63,  77,  209; 
structure  of  Curtiss  biplane, 
65>  77,  92>  2I4J  structure  of 
Farman  machine,  69,  74,  77, 
105,  217  et  seq.;  Voisin  (old 
tyPe)>  74;  Voisin  (new  type), 
75>  77)  78>  I05;  structure  of 
Sommer  machine,  77,  220  et 
seq.;  structure  of  Breguet 
machine,  78;  structure  of 
Voisin  (new  type),  78,  105; 
structure  of  Goupy,  78;  struc- 
ture of  Caudron  Freres,  78; 
margin  of  safety,  172  et  seq. 

BIRDS 

relation  to  aeroplanes,  2,  5, 
9;  launching  devices  of  birds, 
10,  45;  vultures  in  open 
cages  and  reason  therefor,  12; 
birds  and  machines  in  alight- 
ing, 13;  efficiency,  15,  in, 
113;  proportions  and  shapes 
of  wings,  16,  27;  Lanchester 
on  bird  flight,  113 

BISMARCK 

on  air-spies,  262 

BlTTERFELD 

aerological  observatory,  158 
BLACKSTONE 

on  ownership  of  the  air,  248 
BLADES,  PROPELLER  (See  Screw) 
BLERIOT,  Louis  (See  also  Mono- 
planes) 

his  use  of  the  dihedral  angle, 

74;  his  cross-Channel  flight, 

112,  239;  his  experiences,  225 

BLUE  HILL  OBSERVATORY    (See 

Rotch,  A.  Lawrence) 
BOATS 

comparison  of  wind  effects 
on  boats  and  planes,  35 
BOMBS  (See  also  War) 

as  an  offensive  weapon,  186 


INDEX 


283 


BRAKES 

use  in  alighting,  57 
BRETT,  MASTER  OF  THE  ROLLS, 

on  law  of  the  air,  248 
BREWER,  R.  W.  A. 

his  aeroplane  of  the  future, 
236 
BRYAN,  G.  H. 

on  equilibrium  and  stabil- 
ity, 1 68 


CAMBER 

of  propellers,  96 
CAUDRON     FRERES     (See     Bi- 
planes} 

CANNON,  AERIAL  (See  Ordnance} 
CANTING  (See  Gravitation,  Steer- 
ing) 
CENTRIFUGAL  FORCE 

its   effect   in   steering,    87; 
in  screw  propellers,  95 
CHANUTE,  OCTAVE 

his  gliders,  7,   19,  42;    his 
use  of  the  truss,  17;    his  de- 
scription of  Wright  Brothers' 
learning  to  turn,  89 
CHAUVIERE    PROPELLERS    (See 
-    Screw} 
CHAVEZ 

cause  of  death,  176;    acci- 
dent at  Nice,  233 
CIRCUIT  DE  L'EST 

motor  trouble,  130;   physi- 
cal endurance  test,  165 
CLEMENT-BAYARD  MOTORS  (See 

Motors) 
COKE  UPON  LITTLETON 

ownership  of  the  air,  248 
COMPASS 

for  aerial  use,  234 
CONDOR  (See  also  Birds) 

efficiency   as  a  flying  ma- 
chine, 112 
CORNU 

his  helicopter,  23 
CRIME  IN  THE  AIR  (See  Law, 

Aerial 
CROCHON 

cause  of  his  death,  232 


CURTISS,  GLENN  H.    (See  also 
Biplane,      Monoplane,      and 
Motors 
Hudson  River  flight,  160, 165 

DAEDALUS 

his  ornithopter,  23 
D'AMECOURT,  PONTON 

relation  to  helicopter,  21  ^ 
DANGERS  OF  AIRMEN  (See  Acci- 
dents) 
DA  VINCI,  LEONARDO 

his    ornithopter,    24;     his 
screw  propeller,  94 
DE  BORT,  TEISSERENC 

meteorological  studies,  137, 
140,  143,  144,  149 
DELAGRANGE 

cause  of  death,  176 
DE  LA  HAULT,  ADH. 

ornithopter  experiments,  24 
DE  LA  LANDELLE 

his  relation  to  helicopter,  21 
DE  LA  ROCHE,  BARONESS 

accident  at  Reims  (1910), 
172 

DIHEDRAL    ANGLE     (See    Sta- 
bility) 
DIRIGIBLE  AIRSHIP  IN  WAR  (See 

War} 
DOVER 

wind  surf,  164 
DUCKS 

their  difficulty  in  starting, 
ii 
Du  TEMPLE 

his  propeller,  99 

EAGLE 

compared  with  kite,  2;  how 
launched  in  flight,  10 
EHRHARDT   AUTOMOBILES    (See 

Automobiles) 
EIFFEL 

aerodynamic    experiments, 

ELY 

his  landing  on  deck  of  war- 
ship, 238 
ENGINES  (See  Motors) 


284 


INDEX 


ENTERING  EDGE 

relation  to  lifting  power,  27; 
Lilienthal's  investigation,  28; 
Phillip's  study,  28;  Langley's 
results,  28;  Wright  Brothers' 
studies,  28 

E.  N.  V.  MOTORS  (See  Motors) 
EQUILIBRIUM  (See  also  Stability) 
of  yachts  and   aeroplanes, 
3;    distinguished  from  stabil- 
ity, 1 68 
ERICSSON 

his  marine  propeller,  99 
ESNAULT-PELTERIE,  ROBERT 
his  stability  control  system, 

EXPLORATION 

geographical      and      topo- 
graphical value  of  the  flying- 
machine,  235 
EXPLOSIVES 

use  on  aeroplanes,  186; 
shrapnel  for  repelling  attack, 
20 1 


FARMAN,  HENRY 

his   launching   device,    53; 

use     and     abandonment     of 

early     Voisin     biplane,     75; 

winning  of  Armengaud  prize, 

89;       influence     of     Wright 

Brothers,  217 
FAUCHILLE 

on     permissible     altitude, 

2S°>     2S9>      criminal     aerial 

jurisdiction,  261 
FIAT  MOTORS  (See  Motors) 
FLAPPING-WING  MACHINES  (See 

Ornithopters) 
FLY-WHEEL 

its     function,     115,'    117; 

rotary  engines  as  fly-wheels, 

127 

FRICTION  (See  Skin  Friction) 
FRIEDRICHSHAFEN 

observatory,  138,  159 
FUEL  (See  Petrol  and  Gasoline) 
FUTURE,   FLYING-MACHINE  OF 

THE,  231  et  seq.,  240,  242 


GASOLINE 

its  use  as  a  fuel,  115,  117 
GLIDING 

its   relation  to  safe  flight, 
18,  189 
GLOSSOP  MOOR 

aerological  observatory,  138 
GNOME  MOTORS  (See  Motors) 
GOULD,  EDWIN 

prize   for  multimotor  ma- 
chine, 182 

GOUPY  (See  Biplanes) 
GRAVITATION 

its  part  in  aeroplane  flight, 
J»  4»  3i»  59;   in  steering,  87 
GRAVITY,  CENTER  OF 

relation  to  center  of  air 
pressure,  4;  shifting  center 
of  gravity  to  maintain  bal- 
ance, 5,  8;  in  Lillienthal's 
machine,  6;  in  Pilcher's 
machine,  7;  in  Chanute's 
gliders,  7;  relation  to  stabil- 
ity,  85 
GRUNWALD 

on  international  law  of  the 
air,  257 

GUNS,  AERIAL  (See  Ordnance) 
GYROSTAT 

its    use    in    automatically 
maintaining  balance,  80,  82 

HAGUE  PEACE  CONFERENCE 

on  use  of  bombs,  187;    on 
spies  in  the  air,  263 
HARGRAVE,  LAWRENCE 

ornithopter  experiments,  24 
HAZELTINE 

on     international     law    of 
air,  256,  259 
HELICOPTERS 

principle  of  screw-fliers,  20; 
d'Amecourt  and  de  la  Lan- 
delle,  21 ;  Renard's  screw- 
flier,  22;  Edison's  helicopter, 
22;  Berliner's  helicopter,  23; 
Cornu's  helicopter,  23;  Bre- 
guet,  23;  Kress,  102 
HELIX  (See  Screw) 


INDEX 


285 


HENSON 

his  propeller  designs,  99 
HERRING 

determination  of  effect  of 
wires  and  struts  on  speed,  34; 
invention  of  skids,  55 

HOLTZENDORFF 

on  international  law  of  the 
air,  257,  259 

HOUBERNAT  GUN  (See  Ordnance} 
HYGROMETER 

use  in  meteorology,  134, 
139 


INCIDENCE,  ANGLE  OF 

maintenance  of  horizontal 
flight  by  adjustment  of  angle 
of  incidence,  31,  59,  60; 
cause  of  variations  in  the 
angle,  32;  gyrostat  and  angle 
of  incidence,  80 
INSELBERG 

Aerological      Observatory, 

T    IS8 

INSURANCE 

Baldwin    on    accident    in- 
demnities, 252 

INTERNATIONAL  CONFERENCE 
ON  AERIAL  NAVIGATION  (See 
Paris  Conference) 

ISOTHERMAL  STRATUM  (See  At- 
mosphere) 


JEFFRIES 

meteorological  studies,  136 


KEELS  (See  also  Stability) 

their  stabilizing  effect,  75 

KITES 

kites  and  aeroplanes  com- 
pared, 2;  stability  of  kites 
and  manner  of  maintaining 
it,  9;  launching,  9;  stability 
of  box  and  single-surface 
kites  compared,  16;  use  in 
meteorology,  136,  139,  142, 
143 


KRESS 

his  propeller  system,  102 
KRUPP  AERIAL  ARTILLERY  (See 

Ordnance) 
KUHN,  ARTHUR  K. 

on  international  law  of 
the  air,  236  et  seq.',  spies  in 
the  air,  263 


LANCHESTER,  F.  W. 

on  automatic  stability,  76; 
on  speed,  236 
LANDING  (See  Alighting) 
LANGLEY,  SAMUEL  PIERPONT 

comparison  of  eagle  and 
aeroplane,  10;  his  launching 
experiments,  12,  42;  ex- 
periments with  planes,  16; 
determination  of  lift  of  aero- 
curves,  28;  determination  of 
power  ratio  for  given  speed, 
33,  243;  his  trials  with  large 
aerodrome,  49;  newspaper 
derision,  50;  use  of  the  dihe- 
dral angle,  74;  adoption  of 
rear  horizontal  rudder,  78; 
his  propellers,  100,  107;  study 
of  bird  efficiency,  in;  motor 
designs,  n6j  wind  studies, 

T     l63 

LARK 

aspect  ratio,  16 

LATHAM,    HUBERT     (See    also 
Monoplanes) 

at  Belmont  Park  (1910), 
224;  accident  at  Nice,  233 

LAUNCHING 

necessity  of  preliminary 
run,  9,  10,  42;  methods  of 
getting  up  preliminary  speed, 
12,  44;  Langley's  experi- 
ments, 12;  Wright  Brothers' 
methods,  12;  wheels  for 
launching,  12,  13;  Langley's 
difficulties,  42;  Wright  start- 
ing derrick  and  rail,  52; 
power  consumed  in  launching, 

e;     adoption   of  wheels   by 
irtiss  and  Farman;  Wright 


286 


INDEX 


adoption  of  wheels,  54;  gyro- 
stats and  their  effect,  80; 
launching  grounds  of  the 
future,  237 

LAW,  AERIAL 

adaptability  of  common 
law,  246;  salvage,  247;  own- 
ership of  air,  248;  code  of 
Canton  of  Grisons,  249; 
German  Civil  Code,  249; 
permissible  altitude,  250, 
258;  trespass,  250;  com- 
pulsory alighting,  251;  li- 
censes, 253;  international 
aspects,  253,  256  et  seq.; 
aerial  equivalent  of  maritime 
three-mile  limit,  258;  crimi- 
nal jurisdiction,  261;  spies 
in  the  air,  263;  rights  of 
neutrals,  267 

LEBLANC 

in  Circuit  de  I'Est,  131;  at 
Havre  (1910),  166 

LEBLON,  HUBERT 

cause  of  death,  182,  233 

LEVAVASSEUR  (See  also  Mono- 
planes [Antoinette]) 
propeller  mounting,  100 

LICENSES 

Baldwin  on  licenses,  252 

LIFT 

relation  to  entering  edge, 
27;  to  angle  of  incidence,  31; 
Maxim's  experiments,  28; 
Phillip's  work,  28;  Langley's 
studies,  28,  34;  Wright  Broth- 
ers' studies,  28,  34;  effect  of 
turning  on  lift,  87 

LIGHTHOUSES 

beacons  for  aviators,  234 

LlLIENTHAL,  OTTO 

cause  of  his  death,  5;  his 
gliders,  6,  8,  19,  42;  experi- 
ments in  determining  lifting 
effect,  28 

LlNDENBERG 

Aeronautical  Observatory, 
138,  154,  ISS,  156 

LlNDPAINTNER 

In  Circuit  de  FEst,  131 


LlNFIELD 

his  propeller  design,  99 
LINKE 

his  aeronautic  weather  ser- 
vice, 155 
LUBRICATION 

of  motors,  124,  128 


MACOMB,  MAJOR 

on  Langley's  aerodrome,  49 
MAPS 

use  by  aviators,  160 
MAXIM,  SIR  HIRAM 

experiments      on      lift     of 
curved     surfaces,     28;      pro- 
peller designs,  100,  101,  107 
MEURER 

on     international    law     of 


on  law  of  the  air,  247,  253 
METALLURGIC  (See  Motors) 
METEOROGRAPHS     (See     Mete- 

orology) 
METEOROLOGY 

relation   to   flying,    133    et 
seq.\    dates  for  international 
aerological  investigations,  145 
MEUNIER,  GENERAL 

on  aerial  scouting,  190 
MILITARY     USES     OF     FLYING 
MACHINES 

aeroplane  in  war,  186  et  seq. 
MILLER,  WARREN  H. 

his  table  of  motor  efficien- 
cies, 131 
MODELS 

relative  advantages  of  fixed 
and    moving    models    in    re- 
search work,  40 
MOISANT 

cross-Channel  flight,  164 
MONOPLANE 

compared'  with  skate,  i; 
distinguished  from  biplanes, 
15;  structural  defects,  17; 
advantage  of  its  single  sur- 
face, 18;  relative  perfection 
of  monoplane  and  biplane, 


INDEX 


287 


1 8;  speed  of  Bleriot,  35; 
alighting  gear  of  Antoinette, 
56,  223;  of  Pelterie,  57; 
Bleriot  construction,  70,  78, 
100,  105,  225;  Antoinette 
construction,  72,  75,  78,  100, 
105,  222;  use  of  dihedral 
angle  by  Langley  and  Bleriot, 
74;  Hanriot  monoplane,  76; 
Santos-Dumont  monoplane, 
92,  100,  228;  Curtiss  mono- 
plane, 217;  margin  of  safety, 
172 

MORANE 

at  Havre  meeting  (1910), 
166 

MOTOR-CAR    GUNS    (See  Auto- 
mobiles) 

MOTORS 

relation  to  speed,  17;  to 
angle  of  incidence,  32;  di- 
minishing power  required  with 
increasing  speed  (Langley's 
law)  33;  power  consumed 
in  starting  machine,  53,  54; 
low  power  of  early  Wright 
motors,  54;  relation  to  pro- 
pellers, 108;  efficiency,  in, 
116,  129,  205;  Anzani,  112, 
132,  226;  Wright,  112,  116, 
129,  132,  213;  4-cycle  princi- 
ple, 113;  lightness,  117,  232; 
cylinder  arrangements,  117; 
lubrication,  124;  radial  en- 
gines, 124;  Gnome  motors, 
126,  127,  129,  132,  219,  220, 
224,  227;  Antoinette  motors, 
129,  132,  224;  Fiat  motors, 
129;  Metallurgic,  129;  Re- 
nault, 129;  automobile  mo- 
tors, 129,  224;  E.  N.  V. 
motors,  13  2;  Clement-Bayard, 
132,  230;  Curtiss,  216;  R.  E. 
P.  motors,  132;  motor-break- 
downs, 182,  205;  effect  of 
rarefied  air  on  compression,2O5 

MOY 

his  fan-propeller,  99 

MT.  WEATHER  OBSERVATORY 
its  functions,  137 


MULTIPLANE 

triplanes,  19,  20;    Phillips, 
20 


NEUTRALITY  IN  AIR  WARFARE 
(See  Law,  Aerial) 


ORDNANCE,  AERIAL 

for  repulsion  of  aerial  at- 
tacks, 196;  Krupp  guns, 
197  et  seq.,  258;  Rheinische 
Metallwaaren  und  Maschi- 
nenfabrik  (Dlisseldorf)  aerial 
guns,  199,  201;  Houbernat 
gun,  200;  machine-guns  on 
aeroplanes,  202,  204;  range 
of  Krupp  guns  to  determine 
neutral  zone,  258 

ORNITHOPTERS 

underlying  principle,  23 ; 
Leonardo  da  Vinci's,  24; 
Allard's  experiments,  24;  Har- 
grave's  models,  24;  de  la 
Hault's  experiments,  24;  dis- 
advantages of  the  type,  25 

OTTO  ENGINE  (See  Motors) 


PARIS  CONFERENCE 

international    law    of    the 
air,  253,  260,  266,  267 
PATENTS 

Wright  patents   and   their 
scope,    67,    68,    69,    70,    75; 
Wright  pendulum  patents,  79 
PAVIA 

Aerological      Observatory, 

T,'38 

PAVLOVSK 

Aerological      Observatory, 

T,'38 

PENDULUM 

Wright  automatic  pendu- 
lum for  stabilizing,  79;  faults 
of  the  pendulum  as  an  auto- 
matic control  device,  81 

PERMANENT  INVERSION  LAYER 
(See  Atmosphere) 


288 


INDEX 


PETROL 

as  a  motor  fuel,  115,  117 
PHILLIPS,  HORATIO 

his  multiplane,  20;    study 
of    lifting    effect    of    curved 
planes,  28 
PHOTOGRAPHY 

the   camera    in   war,    189, 
264;    in  exploration,  236 
PICQUART,  GENERAL 

on  aerial  scouting,  190 

PlLCHER 

his  death,  7;    gliders,  42, 
170 
PITCH 

definition,  96 

PLANES  (See  also  Lift,  Entering 
Edge) 

Proper  shape  and  size,  16; 
relation  to  hull  of  a  ship,  26, 
27;  entering  edge  and  lift, 
27;  Lilienthal's  results,  28; 
Wright  Brothers'  studies  of 
aerocurve  lifts,  28;  Phillips 
study  of  lifts,  28;  force  act- 
ing on  plane  in  motion,  31; 
angle  of  incidence  and  speed, 
31;  relation  of  power  to 
speed,  33,  243  (Langley's 
law);  speed  and  size  of 
planes,  36;  reefing  wings, 
37;  aerodynamic  studies,  38; 
margin  of  safety,  172 

POLIS 

his  aeronautic  weather  ser- 
vice, 155 

POWER  (See  Motors) 

PRANDTL 

aerodynamic  work  at  Goet- 
tingen,  41;  exposure  of  pen- 
dulum defects  for  automatic 
control,  82;  study  of  form 
for  airship  gas  bags,  227 

PRESSURE 

relation  of  pressure  to 
entering  edge,  28;  aero- 
dynamic study  of  pressure, 
38;  pressure  and  support  of 
machine  in  flight,  59;  effect 
on  construction,  177 


PRESSURE,  CENTER  OF 

relation  of  center  of  gravity 
to,  4;  shifting  center  of  pres- 
sure to  maintain  balance,  5; 
in  Lilienthal's  glider,  6;  in 
Pilcher's  machine,  7;  in 
Chanute's  glides,  7;  in  Wright 
machines,  8;  automatic  con- 
trol, 9 

PROJECTILES  (See  Explosives') 

PROPELLERS  (See  Screw) 

PTERODACTYL 

efficiency  compared  with 
flying  machine,  in 

RACING 

its    effect    on    commercial 
development     of     aeroplane, 
240 
RADIATORS 

in  motors,  116 
RAILS     IN     LAUNCHING     (Set 

Launching) 
RECONNAISSANCE 

scouting    aeroplanes,    189, 
190 
REGNARD,  PAUL 

his    gyrostatic   system    of 
control,  80 
REIMS 

meeting  of  1910  and  speeds 
attained,  35;    accidents,  172, 
^176,  179 
RENARD,  COLONEL 

his  combined  aeroplane  and 
helicopter,  22 

RENAULT  MOTORS  (See  Motors) 
R.  E.  P.   (See  Esnault-Pelterie 

and  Motors') 

RESISTANCE  (See  Pressure) 
RHEINISCHE      METALLWAAREN 
UNO  MASCHINENFABRIK  AE- 
RIAL   ARTILLERY    (See    Ord- 
nance) 
RHINOW 

Lilienthal's  experiments 
at,  6 

ROLLAND 

on  international  law  of  the 
air,  259 


INDEX 


289 


ROLLS,  C.  S. 

cause  of  death,  171,  176 

ROTCH,  A.  LAWRENCE 

meteorological  studies,  137, 
141 

RUDDERS,  HORIZONTAL  (See  also 
Steering) 

their  purpose,  13,  167; 
Wright  system,  64,  77,  210; 
Curtiss  system,  65,  77,  214; 
Farman  system,  69,  77,  218; 
Bleriot  system,  72,  226;  An- 
toinette system,  72,  223; 
stabilizing  effect  when  used 
as  tails,  77;  Langley  system, 
78,  129;  Sommer  system, 
220;  Santos-Dumont  (De- 
moiselle) system,  229 

RUDDERS,   VERTICAL   (See  also 
Steering) 

their  necessity,  13;  use 
in  maintaining  stability  as 
taught  by  the  Wrights,  63; 
Curtiss  system,  65,  215; 
Farman  system,  69,  219; 
Bleriot  system,  72,  226;  An- 
toinette system,  72,  223; 
Wright  system,  210;  Santos- 
Dumont  system,  229;  effect  of 
vertical  rudder  in  steering,  92; 
types  of  vertical  rudders,  92 


SAFETY  (See  Occidents) 

SALVAGE  (See  Law,  Aerial) 

SCOUTING 

aeroplane  reconnaissances, 
189,  190 

SCREW 

lifting  propellers  in  heli- 
copters, 21 ;  inefficiency  of 
screw,  94,  106,  108;  da  Vin- 
ci's screw,  94;  principle  of 
screw,  95  et  seq.;  Ericsson's 
marine  propeller,  99;  Moy's 
fan  propeller,  99;  Henson's 
propeller,  99;  Stringfellow's 
propeller,  99;  Linfield's  pro- 
peller, 99;  du  Temple's  pro- 
peller, 99;  Langley's  pro- 


pellers, 100;  Maxim's  pro- 
pellers, ico;  Kress  system, 
102;  Wright  system,  103, 
109;  Chauviere,  104,  109, 
no,  219,  227,  230;  danger  of 
breakage,  181;  Curtiss  pro- 
pellers, 216 

SCREW-FLIERS  (See  Helicopters) 

SELFRIDGE 

his  death,  103,  181 

SHELLS  (See  Explosives) 

SHIPS  (See  also  Yachts,  Boats) 

difference  between  aero- 
planes and  ships  in  axis  of 
propulsion,  27;  comparison  of 
towing-tank  experiments  and 
aerodynamic  researches,  38 

SHOCK-ABSORBERS     (See     also 
Alighting) 

necessity  of,  55 

SHRAPNEL  (See  Explosives) 

SIDO,  LIEUTENANT 

performances  as  an  aerial 
scout,  191 

SKIDS  (See  also  Alighting) 

use  in  alighting,  55;  intro- 
duction by  Herring  and 
Wrights,  55;  use  by  Farman, 
56, 219;  Sommer,  56;  Santos- 
Dumont  and  Antoinette,  56 

SKIN-FRICTION 

its  laboratory  study,  38; 
in  screw  propellers,  96 

SLIP 

definition,  96;  speed  and 
slip,  104 

SOMMER,  ROGER 
his  biplane,  220 

SOUNDING-BALLOONS  (Set  Bal- 
loons) 

SPAN  (See  Aspect  Ratio) 

SPEED  (See  also  Motors) 

tails  and  their  effect,  17; 
relation  of  speed  to  form,  26; 
relation  to  gravitation,  31; 
effect  on  angle  of  incidence, 
32;  power  and  speed  in  aero- 
planes, 33,  34;  monoplane 
speeds,  35;  relation  of  speed 
to  wind,  35;  landing  at  high 


290 


INDEX 


speed,  36;  necessity  of  vari- 
able speed,  36,  243;  speec 
and  stability,  75;  speed  and 
steering,  87;  speed  and  mo- 
tors, 130;  speed  and  struc- 
tural design,  177,  179;  speec 
of  future  aeroplane,  236 
SPY,  AERIAL 

repulsion  of,  196 
SQUIER,  MAJOR  G.  O. 

on  military  possibilities  oJ 
aerial  navigation,  195 
STABILITY 

in  birds,  3;  in  machines, 
4;  methods  of  maintaining 
stability,  5;  fore-and-aft  sta- 
bility, 8,  14,  167;  automatic 
control,  9,  75,  79,  83,  169, 
223;  monoplane  and  biplane 
stability  compared,  16;  sta- 
bility explained,  58;  aile- 
rons and  their  use,  61;  Wright 
warping  system,  63,  210; 
Curtiss  system,  65,  92,  215; 
Wright-Curtiss  infringement 
suit,  67;  Farman  control,  69, 
218,  220;  Bleriot  control,  70, 
226;  Antoinette  control,  72, 
223;  the  efficiency  of  the 
dihedral  angle,  74,  170;  use  of 
vertical  curtains  (Voisin),  74; 
effect  of  keels,  75;  Lanchester 
on  speed  and  stability,  75; 
Esnault-Pelterie  control,  77; 
use  of  tails  to  maintain 
fore-and-aft  stability,  77,  210; 
gyrostatic  control,  80;  au- 
tomatic vs.  hand  control,  80; 
stability  and  steering,  88; 
effect  of  wind,  91;  Santos- 
Dumont  control  system,  92; 
dangers  of  bad  manipulation 
of  stabilizers,  167;  equilib- 
rium and  stability  distin- 
guished, 168;  Sommer  system 
of  control,  220 
STARTING  (See  Launching) 
STAYS  (See  also  Wires) 

in     monoplanes     and     bi- 
planes, 173  et  seq. 


STEERING  (See  also  Rudders) 

necessity  for  two  sets  of 
rudders,  13;  Wright  system, 
64;  Curtiss  system,  65;  Far- 
man system,  69;  Antoinette 
system,  72;  principles  in- 
volved in  steering,  85  et  seq.'t 
perils  of  steering,  170 

STRINGFELLOW 

his  triplane,  20;  his  pro- 
peller designs}  99 

TAILS 

their   part   in   maintaining 
stability,   9,    14,    17,   77,   79, 
212,  219,  221,  226 
TAUNUS 

Aerological      Observatory, 
158 
TELEGRAPHY,  WIRELESS 

on  aeroplanes  in  war,  193; 
Berlin  Conference,  251 
THEODOLITES 

use  in  meteorology,  143 
THERMOMETER 

use  in  meteorology,  134, 
139 

THRUST  (See  Screw) 
TOWING-CARRIAGES 

defects  of,  39 
TRACTOR  SCREWS  (See  Screws) 
TRAPPES 

aerological  work,  138 
TRESPASS  (See  Law  of  the  Air) 
TRIPLANE  (See  Multiplane) 
TURKEY-BUZZARD      (See      also 
Birds) 

efficiency    as   a   flying-ma- 
chine, 112 
TURNING  (See  Steering) 

VAN  MAASDYSK 

cause  of  death,  182 
VOL-PLANE  (See  Gliding) 
VOISIN  FRERES  (See  Biplanes) 
VULTURES 

how  launched  for  flight,  10; 
how  caged  and  reason  there- 
for, 12 


INDEX 


291 


WACHTER 

cause  of  death,  176,  179 

WAR, 

flying-machines  in,  185  et 
seq.\  dirigibles  vs.  aeroplanes 
in  war,  202;  double-motor 
military  machine,  232;  inter- 
national law  and  aerial  war- 
fare, 262 

WARPING  (See  Stability) 

WATER-JACKET 
use  in  motors,  n 6 

WEATHER 

weather  and  flight,  133 
et  seq. 

WESTLAKE 

on  international  law  of  the 
air,  258 

WHEELS  FOR  ALIGHTING  AND 
LAUNCHING  (See  Launching 
and  Alighting) 

WHIRLING-TABLES 
their  defects,  40 

WIND 

relation  of  speed  to  wind, 
35;  effect  on  launching,  46; 
effect  on  steering,  91;  use 
of  anemometer,  134;  wind- 
data  of  German  Empire,  154; 
wind  perils,  163,  170;  wind- 
gauges  for  dropping  explo- 
sives, 187 

WINGS  (See  Planes) 

WIRES 

effect  on  speed,  33;   use  in 


stiffening     monoplanes     and 
biplanes,  173  et  seq. 

WIRELESS     TELEGRAPHY     (See 
Telegraphy) 

WRIGHT  BROTHERS 

their  contribution  to  flight 
problem,  8;  launching  de- 
vices, 12,  51;  study  of  lift 
of  curved  surfaces,  28;  on 
variability  of  angle  of  inci- 
dence, 33;  study  of  relation 
of  power  to  speed  (Langley's 
law),  34;  influence  of  Langley 
on  Wrights,  51;  introduc- 
tion of  skids,  55;  their  solu- 
tion of  stability  problem,  61, 
63;  rudder  studies,  77; 
automatic  stability  patents, 
79;  Chanute  on  their  early 
turning  experiments,  89;  ac- 
cident to  Orville  Wright  at 
Ft.  Myer,  103,  181;  skill  in 
aviation,  166,  167;  scientific 
character  of  their  work,  183; 
influence  on  Farman,  217; 
Orville  Wright  on  future  of 
aeroplane,  243 


YACHTS  (See  also  Boats,  Ships) 
compared  with  aeroplanes 
in  stability,  3;  compared  with 
aeroplane  in  making  a  turn, 
91 


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